Full List of INPUT Keywords

• Full List of INPUT Keywords

  • System variables

    • suffix

    • ntype

    • calculation

    • esolver_type

    • symmetry

    • symmetry_prec

    • symmetry_autoclose

    • kpar

    • bndpar

    • latname

    • psi_initializer

    • init_wfc

    • init_chg

    • init_vel

    • nelec

    • nupdown

    • dft_functional

    • xc_temperature

    • pseudo_rcut

    • pseudo_mesh

    • mem_saver

    • diago_proc

    • nbspline

    • kspacing

    • min_dist_coef

    • device

    • precision

  • Variables related to input files

    • stru_file

    • kpoint_file

    • pseudo_dir

    • orbital_dir

    • read_file_dir

    • wannier_card

  • Plane wave related variables

    • ecutwfc

    • ecutrho

    • nx, ny, nz

    • ndx, ndy, ndz

    • pw_seed

    • pw_diag_thr

    • pw_diag_nmax

    • pw_diag_ndim

    • erf_ecut

    • fft_mode

    • erf_height

    • erf_sigma

  • Numerical atomic orbitals related variables

    • nb2d

    • lmaxmax

    • lcao_ecut

    • lcao_dk

    • lcao_dr

    • lcao_rmax

    • search_radius

    • search_pbc

    • bx, by, bz

  • Electronic structure

    • basis_type

    • ks_solver

    • nbands

    • nbands_istate

    • nspin

    • smearing_method

    • smearing_sigma

    • smearing_sigma_temp

    • mixing_type

    • mixing_beta

    • mixing_ndim

    • mixing_gg0

    • mixing_tau

    • mixing_dftu

    • gamma_only

    • printe

    • scf_nmax

    • scf_thr

    • scf_thr_type

    • chg_extrap

    • lspinorb

    • noncolin

    • soc_lambda

  • Electronic structure (SDFT)

    • method_sto

    • nbands_sto

    • nche_sto

    • emin_sto

    • emax_sto

    • seed_sto

    • initsto_ecut

    • initsto_freq

    • npart_sto

  • Geometry relaxation

    • relax_method

    • relax_new

    • relax_scale_force

    • relax_nmax

    • relax_cg_thr

    • cal_force

    • force_thr

    • force_thr_ev

    • force_thr_ev2

    • relax_bfgs_w1

    • relax_bfgs_w2

    • relax_bfgs_rmax

    • relax_bfgs_rmin

    • relax_bfgs_init

    • cal_stress

    • stress_thr

    • press1, press2, press3

    • fixed_axes

    • fixed_ibrav

    • fixed_atoms

    • cell_factor

  • Variables related to output information

    • out_mul

    • out_freq_elec

    • out_chg

    • out_pot

    • out_dm

    • out_dm1

    • out_wfc_pw

    • out_wfc_r

    • out_wfc_lcao

    • out_dos

    • out_band

    • out_proj_band

    • out_stru

    • out_bandgap

    • out_level

    • out_alllog

    • out_mat_hs

    • out_mat_r

    • out_mat_hs2

    • out_mat_t

    • out_mat_dh

    • out_app_flag

    • out_interval

    • out_element_info

    • restart_save

    • restart_load

    • rpa

  • Density of states

    • dos_edelta_ev

    • dos_sigma

    • dos_scale

    • dos_emin_ev

    • dos_emax_ev

    • dos_nche

  • NAOs

    • bessel_nao_ecut

    • bessel_nao_tolerence

    • bessel_nao_rcut

    • bessel_nao_smooth

    • bessel_nao_sigma

  • DeePKS

    • deepks_out_labels

    • deepks_scf

    • deepks_model

    • bessel_descriptor_lmax

    • bessel_descriptor_ecut

    • bessel_descriptor_tolerence

    • bessel_descriptor_rcut

    • bessel_descriptor_smooth

    • bessel_descriptor_sigma

    • deepks_bandgap

    • deepks_out_unittest

  • OFDFT: orbital free density functional theory

    • of_kinetic

    • of_method

    • of_conv

    • of_tole

    • of_tolp

    • of_tf_weight

    • of_vw_weight

    • of_wt_alpha

    • of_wt_beta

    • of_wt_rho0

    • of_hold_rho0

    • of_lkt_a

    • of_read_kernel

    • of_kernel_file

    • of_full_pw

    • of_full_pw_dim

  • Electric field and dipole correction

    • efield_flag

    • dip_cor_flag

    • efield_dir

    • efield_pos_max

    • efield_pos_dec

    • efield_amp

  • Gate field (compensating charge)

    • gate_flag

    • zgate

    • block

    • block_down

    • block_up

    • block_height

  • Exact Exchange

    • exx_hybrid_alpha

    • exx_hse_omega

    • exx_separate_loop

    • exx_hybrid_step

    • exx_mixing_beta

    • exx_lambda

    • exx_pca_threshold

    • exx_c_threshold

    • exx_v_threshold

    • exx_dm_threshold

    • exx_c_grad_threshold

    • exx_v_grad_threshold

    • exx_schwarz_threshold

    • exx_cauchy_threshold

    • exx_cauchy_force_threshold

    • exx_cauchy_stress_threshold

    • exx_ccp_threshold

    • exx_ccp_rmesh_times

    • exx_distribute_type

    • exx_opt_orb_lmax

    • exx_opt_orb_ecut

    • exx_opt_orb_tolerence

    • exx_real_number

  • Molecular dynamics

    • md_type

    • md_nstep

    • md_dt

    • md_thermostat

    • md_tfirst, md_tlast

    • md_restart

    • md_restartfreq

    • md_dumpfreq

    • dump_force

    • dump_vel

    • dump_virial

    • md_seed

    • md_tfreq

    • md_tchain

    • md_pmode

    • md_prec_level

    • ref_cell_factor

    • md_pcouple

    • md_pfirst, md_plast

    • md_pfreq

    • md_pchain

    • lj_rcut

    • lj_epsilon

    • lj_sigma

    • pot_file

    • msst_direction

    • msst_vel

    • msst_vis

    • msst_tscale

    • msst_qmass

    • md_damp

    • md_tolerance

    • md_nraise

    • cal_syns

    • dmax

  • DFT+U correction

    • dft_plus_u

    • orbital_corr

    • hubbard_u

    • yukawa_potential

    • yukawa_lambda

    • omc

  • vdW correction

    • vdw_method

    • vdw_s6

    • vdw_s8

    • vdw_a1

    • vdw_a2

    • vdw_d

    • vdw_abc

    • vdw_C6_file

    • vdw_C6_unit

    • vdw_R0_file

    • vdw_R0_unit

    • vdw_cutoff_type

    • vdw_cutoff_radius

    • vdw_radius_unit

    • vdw_cutoff_period

    • vdw_cn_thr

    • vdw_cn_thr_unit

  • Berry phase and wannier90 interface

    • berry_phase

    • gdir

    • towannier90

    • nnkpfile

    • wannier_spin

    • out_wannier_mmn

    • out_wannier_amn

    • out_wannier_eig

    • out_wannier_unk

    • out_wannier_wvfn_formatted

  • TDDFT: time dependent density functional theory

    • td_edm

    • td_print_eij

    • td_propagator

    • td_vext

    • td_vext_dire

    • td_stype

    • td_ttype

    • td_tstart

    • td_tend

    • td_lcut1

    • td_lcut2

    • td_gauss_freq

    • td_gauss_phase

    • td_gauss_sigma

    • td_gauss_t0

    • td_gauss_amp

    • td_trape_freq

    • td_trape_phase

    • td_trape_t1

    • td_trape_t2

    • td_trape_t3

    • td_trape_amp

    • td_trigo_freq1

    • td_trigo_freq2

    • td_trigo_phase1

    • td_trigo_phase2

    • td_trigo_amp

    • td_heavi_t0

    • td_heavi_amp

    • td_out_dipole

    • td_out_efield

    • ocp

    • ocp_set

  • Variables useful for debugging

    • t_in_h

    • vl_in_h

    • vnl_in_h

    • vh_in_h

    • vion_in_h

    • test_force

    • test_stress

    • colour

    • test_skip_ewald

  • Electronic conductivities

    • cal_cond

    • cond_che_thr

    • cond_dw

    • cond_wcut

    • cond_dt

    • cond_dtbatch

    • cond_fwhm

    • cond_nonlocal

  • Implicit solvation model

    • imp_sol

    • eb_k

    • tau

    • sigma_k

    • nc_k

  • Deltaspin

    • sc_mag_switch

    • decay_grad_switch

    • sc_thr

    • nsc

    • nsc_min

    • alpha_trial

    • sccut

    • sc_file

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System variables

These variables are used to control general system parameters.

suffix

• Type: String

• Description: In each run, ABACUS will generate a subdirectory in the working directory. This subdirectory contains all the information of the run. The subdirectory name has the format: OUT.suffix, where the suffix is the name you can pick up for your convenience.

• Default: ABACUS

ntype

• Type: Integer

• Description: Number of different atom species in this calculation. If this value is not equal to the atom species in the STRU file, ABACUS will stop and quit. If not set or set to 0, ABACUS will automatically set it to the atom species in the STRU file.

• Default: 0

calculation

• Type: String

• Description: Specify the type of calculation.

  • scf: do self-consistent electronic structure calculation

  • relax: do structure relaxation calculation, one can use relax_nmax to decide how many ionic relaxations you want

  • cell-relax: do variable-cell relaxation calculation

  • nscf: do the non self-consistent electronic structure calculations. For this option, you need a charge density file. For nscf calculations with planewave basis set, pw_diag_thr should be <= 1e-3

  • get_pchg: For LCAO basis. Please see the explanation for variable nbands_istate

  • get_wf: Envelope function for LCAO basis. Please see the explanation for variable nbands_istate

  • md: molecular dynamics

  • test_memory : checks memory required for the calculation. The number is not quite reliable, please use it with care

  • test_neighbour : only performs neighbouring atom search, please specify a positive search_radius manually.

  • gen_bessel : generates projectors (a series of Bessel functions) for DeePKS; see also keywords bessel_descriptor_lmax, bessel_descriptor_rcut and bessel_descriptor_tolerence. A file named jle.orb will be generated which contains the projectors. An example is provided in examples/H2O-deepks-pw

  • get_S : only works for multi-k calculation with LCAO basis. Generates and writes the overlap matrix to a file named SR.csr in the working directory. The format of the file will be the same as that generated by out_mat_hs2

• Default: scf

esolver_type

• Type: String

• Description: choose the energy solver.

  • ksdft: Kohn-Sham density functional theory

  • ofdft: orbital-free density functional theory

  • sdft: stochastic density functional theory

  • tddft: real-time time-dependent density functional theory (TDDFT)

  • lj: Leonard Jones potential

  • dp: DeeP potential, see details in md.md

• Default: ksdft

symmetry

• Type: Integer

• Description: takes value 1, 0 or -1.

  • -1: No symmetry will be considered.

  • 0: Only time reversal symmetry would be considered in symmetry operations, which implied k point and -k point would be treated as a single k point with twice the weight.

  • 1: Symmetry analysis will be performed to determine the type of Bravais lattice and associated symmetry operations. (point groups, space groups, primitive cells, and irreducible k-points)

• Default:

  • -1: if (dft_fuctional==hse/hf/pbe0/scan0/opt_orb or rpa==True) and calculation!=nscf. Currently symmetry is not supported in EXX (exact exchange) calculation.

  • 0: if calculation==md/nscf/get_pchg/get_wf/get_S or [gamma_only]==True

  • 1: else

symmetry_prec

• Type: Real

• Description: The accuracy for symmetry judgment. Usually the default value is good enough, but if the lattice parameters or atom positions in STRU file is not accurate enough, this value should be enlarged.

  Note: if calculation==cell_relax, this value can be dynamically changed corresponding to the variation of accuracy of the lattice parameters and atom positions during the relaxation. The new value will be printed in OUT.${suffix}/running_cell-relax.log in that case.

• Default: 1.0e-6

• Unit: Bohr

symmetry_autoclose

• Type: Boolean

• Availability: symmetry==1

• Description: Control how to deal with error in symmetry analysis due to inaccurate lattice parameters or atom positions in STRU file, especially useful when calculation==cell-relax

  • False: quit with an error message

  • True: automatically set symmetry to 0 and continue running without symmetry analysis

• Default: True

kpar

• Type: Integer

• Description: divide all processors into kpar groups, and k points will be distributed among each group. The value taken should be less than or equal to the number of k points as well as the number of MPI processes.

• Default: 1

bndpar

• Type: Integer

• Description: divide all processors into bndpar groups, and bands (only stochastic orbitals now) will be distributed among each group. It should be larger than 0.

• Default: 1

latname

• Type: String

• Description: Specifies the type of Bravias lattice. When set to none, the three lattice vectors are supplied explicitly in STRU file. When set to a certain Bravais lattice type, there is no need to provide lattice vector, but a few lattice parameters might be required. For more information regarding this parameter, consult the page on STRU file.

  Available options are (correspondence with ibrav in QE(Quantum Espresso) is given in parenthesis):

  • none: free structure

  • sc: simple cubic (1)

  • fcc: face-centered cubic (2)

  • bcc: body-centered cubic (3)

  • hexagonal: hexagonal (4)

  • trigonal: trigonal (5)

  • st: simple tetragonal (6)

  • bct: body-centered tetragonal (7)

  • so: orthorhombic (8)

  • baco: base-centered orthorhombic (9)

  • fco: face-centered orthorhombic (10)

  • bco: body-centered orthorhombic (11)

  • sm: simple monoclinic (12)

  • bacm: base-centered monoclinic (13)

  • triclinic: triclinic (14)

• Default: none

psi_initializer

• Type: Integer

• Description: enable the experimental feature psi_initializer, to support use numerical atomic orbitals initialize wavefunction (basis_type pw case).

  NOTE: this feature is not well-implemented for nspin 4 case (closed presently), and cannot use with calculation nscf/esolver_type sdft cases. Available options are:

  • 0: disable psi_initializer

  • 1: enable psi_initializer

• Default: 0

init_wfc

• Type: String

• Description: Only useful for plane wave basis only now. It is the name of the starting wave functions. In the future. we should also make this variable available for localized orbitals set.

  Available options are:

  • atomic: from atomic pseudo wave functions. If they are not enough, other wave functions are initialized with random numbers.

  • atomic+random: add small random numbers on atomic pseudo-wavefunctions

  • file: from file

  • random: random numbers

  with psi_initializer 1, two more options are supported:

  • nao: from numerical atomic orbitals. If they are not enough, other wave functions are initialized with random numbers.

  • nao+random: add small random numbers on numerical atomic orbitals

• Default: atomic

init_chg

• Type: String

• Description: This variable is used for both plane wave set and localized orbitals set. It indicates the type of starting density.

  • atomic: the density is starting from the summation of the atomic density of single atoms.

  • file: the density will be read in from a file. Besides, when you do nspin=1 calculation, you only need the density file SPIN1_CHG.cube. However, if you do nspin=2 calculation, you also need the density file SPIN2_CHG.cube. The density file should be output with these names if you set out_chg = 1 in INPUT file.

• Default: atomic

init_vel

• Type: Boolean

• Description:

  • True: read the atom velocity (atomic unit : 1 a.u. = 21.877 Angstrom/fs) from the atom file (STRU) and determine the initial temperature md_tfirst. If md_tfirst is unset or less than zero, init_vel is autoset to be true.

  • False: assign value to atom velocity using Gaussian distributed random numbers.

• Default: False

nelec

• Type: Real

• Description:

  • 0.0: the total number of electrons will be calculated by the sum of valence electrons (i.e. assuming neutral system).

  • >0.0: this denotes the total number of electrons in the system. Must be less than 2*nbands.

• Default: 0.0

nupdown

• Type: Real

• Description:

  • 0.0: no constrain apply to system.

  • >0.0: this denotes the difference number of electrons between spin-up and spin-down in the system. The range of value must in [-nelec ~ nelec]. It is one method of constraint DFT, the fermi energy level will separate to E_Fermi_up and E_Fermi_down.

• Default: 0.0

dft_functional

• Type: String

• Description: In our package, the XC functional can either be set explicitly using the dft_functional keyword in INPUT file. If dft_functional is not specified, ABACUS will use the xc functional indicated in the pseudopotential file. On the other hand, if dft_functional is specified, it will overwrite the functional from pseudopotentials and performs calculation with whichever functional the user prefers. We further offer two ways of supplying exchange-correlation functional. The first is using ‘short-hand’ names such as ‘LDA’, ‘PBE’, ‘SCAN’. A complete list of ‘short-hand’ expressions can be found in the source code. The other way is only available when compiling with LIBXC, and it allows for supplying exchange-correlation functionals as combinations of LIBXC keywords for functional components, joined by a plus sign, for example, ‘dft_functional=‘LDA_X_1D_EXPONENTIAL+LDA_C_1D_CSC’. The list of LIBXC keywords can be found on its website. In this way, we support all the LDA,GGA and mGGA functionals provided by LIBXC.

  Furthermore, the old INPUT parameter exx_hybrid_type for hybrid functionals has been absorbed into dft_functional. Options are hf (pure Hartree-Fock), pbe0(PBE0), hse (Note: in order to use HSE functional, LIBXC is required). Note also that HSE has been tested while PBE0 has NOT been fully tested yet, and the maximum CPU cores for running exx in parallel is \(N(N+1)/2\), with N being the number of atoms. And forces for hybrid functionals are not supported yet.

  If set to opt_orb, the program will not perform hybrid functional calculation. Instead, it is going to generate opt-ABFs as discussed in this article.

• Default: same as UPF file.

xc_temperature

• Type: Real

• Description: specifies temperature when using temperature-dependent XC functionals (KSDT and so on).

• Default : 0.0

• Unit: Ry

pseudo_rcut

• Type: Real

• Description: Cut-off of radial integration for pseudopotentials

• Default: 15

• Unit: Bohr

pseudo_mesh

• Type: Integer

• Description:

  • 0: use our own mesh for radial integration of pseudopotentials

  • 1: use the mesh that is consistent with quantum espresso

• Default: 0

mem_saver

• Type: Boolean

• Description: Used only for nscf calculations.

  • 0: no memory saving techniques are used.

  • 1: a memory saving technique will be used for many k point calculations.

• Default: 0

diago_proc

• Type: Integer

• Availability: pw base

• Description:

  • 0: it will be set to the number of MPI processes. Normally, it is fine just leave it to the default value.

  • >0: it specifies the number of processes used for carrying out diagonalization. Must be less than or equal to total number of MPI processes. Also, when cg diagonalization is used, diago_proc must be the same as the total number of MPI processes.

• Default: 0

nbspline

• Type: Integer

• Description: If set to a natural number, a Cardinal B-spline interpolation will be used to calculate Structure Factor. nbspline represents the order of B-spline basis and a larger one can get more accurate results but cost more. It is turned off by default.

• Default: -1

kspacing

• Type: Real

• Description: Set the smallest allowed spacing between k points, unit in 1/bohr. It should be larger than 0.0, and suggest smaller than 0.25. When you have set this value > 0.0, then the KPT file is unnecessary, and the number of K points nk_i = max(1, int(|b_i|/KSPACING_i)+1), where b_i is the reciprocal lattice vector. The default value 0.0 means that ABACUS will read the applied KPT file. If only one value is set (such as kspacing 0.5), then kspacing values of a/b/c direction are all set to it; and one can also set 3 values to set the kspacing value for a/b/c direction separately (such as: kspacing 0.5 0.6 0.7).

  Note: if gamma_only is set to be true, kspacing is invalid.

• Default: 0.0

min_dist_coef

• Type: Real

• Description: a factor related to the allowed minimum distance between two atoms. At the beginning, ABACUS will check the structure, and if the distance of two atoms is shorter than min_dist_coef*(standard covalent bond length), we think this structure is unreasonable. If you want to calculate some structures in extreme conditions like high pressure, you should set this parameter as a smaller value or even 0.

• Default: 0.2

device

• Type: String

• Description: Specifies the computing device for ABACUS.

  Available options are:

  • cpu: for CPUs via Intel, AMD, or Other supported CPU devices

  • gpu: for GPUs via CUDA or ROCm.

  Known limitations:

  • pw basis: required by the gpu acceleration options

  • cg/bpcg/dav ks_solver: required by the gpu acceleration options

• Default: cpu

precision

• Type: String

• Description: Specifies the precision of the PW_SCF calculation.

  Available options are:

  • single: single precision

  • double: double precision

  Known limitations:

  • pw basis: required by the single precision options

  • cg/bpcg/dav ks_solver: required by the single precision options

• Default: double

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Variables related to input files

These variables are used to control parameters related to input files.

stru_file

• Type: String

• Description: the name of the structure file

  • Containing various information about atom species, including pseudopotential files, local orbitals files, cell information, atom positions, and whether atoms should be allowed to move.

  • Refer to Doc

• Default: STRU

kpoint_file

• Type: String

• Description: the name of the k-points file

  • In atomic orbitals basis with gamma_only set to true, the KPT file is unnecessary, because a KPT file will be generated automatically.

  • When more than one k-points are required, an explicit KPT file is mandatory.

  • Refer to Doc

• Default: KPT

pseudo_dir

• Type: String

• Description: the pseudopotential file directory

  • This parameter is combined with the pseudopotential filenames in the STRU file to form the complete pseudopotential file paths.

  • Example: set pseudo_dir to “…/” with “Si.upf” which specified under “ATOMIC_SPECIES” in STRU file, ABACUS will open the pseudopotential file in path “…/Si.upf”.

• Default: “”

orbital_dir

• Type: String

• Description: the orbital file directory

  • This parameter is combined with orbital filenames in the STRU file to form the complete orbital file paths.

  • Example: set orbital_dir to “…/” with “Si.orb” which specified under “NUMERICAL_ORBITAL” in STRU file, ABACUS will open the orbital file in path “…/Si.orb”.

• Default: “”

read_file_dir

• Type: String

• Description: Indicates the location of files, such as electron density (SPIN1_CHG.cube), required as a starting point.

  • Example: ‘./’ implies the files to be read are located in the working directory.

• Default: OUT.$suffix

wannier_card

• Type: String

• Availability: Using ABACUS with Wannier90.

• Description: The name of the input file related to Wannier90.

• Default: “none”

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Plane wave related variables

These variables are used to control the plane wave related parameters.

ecutwfc

• Type: Real

• Description: Energy cutoff for plane wave functions, the unit is Rydberg. Note that even for localized orbitals basis, you still need to setup an energy cutoff for this system. Because our local pseudopotential parts and the related force are calculated from plane wave basis set, etc. Also, because our orbitals are generated by matching localized orbitals to a chosen set of wave functions from a certain energy cutoff, this set of localize orbitals is most accurate under this same plane wave energy cutoff.

• Default: 50

ecutrho

• Type: Real

• Description: Energy cutoff for charge density and potential, the unit is Rydberg. For norm-conserving pseudopotential you should stick to the default value, you can reduce it by a little but it will introduce noise especially on forces and stress. For ultrasoft pseudopotential a larger value than the default is often desirable (ecutrho = 8 to 12 times ecutwfc, typically). The use of gradient-corrected functional, especially in cells with vacuum, or for pseudopotential without non-linear core correction, usually requires an higher values of ecutrho to be accurately converged.

• Default: 4*ecutwfc

nx, ny, nz

• Type: Integer

• Description: If set to a positive number, then the three variables specify the numbers of FFT grid points in x, y, z directions, respectively. If set to 0, the number will be calculated from ecutrho.

  Note: You must specify all three dimensions for this setting to be used.

• Default: 0

ndx, ndy, ndz

• Type: Integer

• Description: If set to a positive number, then the three variables specify the numbers of FFT grid (for the dense part of charge density in ultrasoft pseudopotential) points in x, y, z directions, respectively. If set to 0, the number will be calculated from ecutwfc.

  Note: You must specify all three dimensions for this setting to be used.

  Note: These parameters must be used combined with nx,ny,nz. If nx,ny,nz are unset, ndx,ndy,ndz are used as nx,ny,nz.

• Default: 0

pw_seed

• Type: Integer

• Description: Only useful for plane wave basis only now. It is the random seed to initialize wave functions. Only positive integers are available.

• Default:0

pw_diag_thr

• Type: Real

• Description: Only used when you use diago_type = cg or diago_type = david. It indicates the threshold for the first electronic iteration, from the second iteration the pw_diag_thr will be updated automatically. For nscf calculations with planewave basis set, pw_diag_thr should be <= 1e-3.

• Default: 0.01

pw_diag_nmax

• Type: Integer

• Description: Only useful when you use ks_solver = cg or ks_solver = dav. It indicates the maximal iteration number for cg/david method.

• Default: 40

pw_diag_ndim

• Type: Integer

• Description: Only useful when you use ks_solver = dav. It indicates the maximal dimension for the Davidson method.

• Default: 4

erf_ecut

• Type: Real

• Description: Used in variable-cell molecular dynamics (or in stress calculation). See erf_sigma in detail.

• Default: 0.0

• Unit: Ry

fft_mode

• Type: Integer

• Description: Set the mode of FFTW.

  • 0: FFTW_ESTIMATE

  • 1: FFTW_MEASURE

  • 2: FFTW_PATIENT

  • 3: FFTW_EXHAUSTIVE

• Default: 0

erf_height

• Type: Real

• Description: Used in variable-cell molecular dynamics (or in stress calculation). See erf_sigma in detail.

• Default: 0.0

• Unit: Ry

erf_sigma

• Type: Real

• Description: In order to recover the accuracy of a constant energy cutoff calculation, the kinetic functional is modified, which is used in variable-cell molecular dynamics (or in stress calculation).

  erf_ecut is the value of the constant energy cutoff; erf_height and erf_sigma are the height and the width of the energy step for reciprocal vectors whose square modulus is greater than erf_ecut. In the kinetic energy, G^2 is replaced by G^2 + erf_height * (1 + erf ( (G^2 - erf_ecut)/erf_sigma) )

  See: M. Bernasconi et al., J. Phys. Chem. Solids 56, 501 (1995), doi:10.1016/0022-3697(94)00228-2

• Default: 0.1

• Unit: Ry

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Numerical atomic orbitals related variables

These variables are used to control the numerical atomic orbitals related parameters.

nb2d

• Type: Integer

• Description: In LCAO calculations, we arrange the total number of processors in an 2D array, so that we can partition the wavefunction matrix (number of bands*total size of atomic orbital basis) and distribute them in this 2D array. When the system is large, we group processors into sizes of nb2d, so that multiple processors take care of one row block (a group of atomic orbitals) in the wavefunction matrix. If set to 0, nb2d will be automatically set in the program according to the size of atomic orbital basis:

  • if size <= 500 : nb2d = 1

  • if 500 < size <= 1000 : nb2d = 32

  • if size > 1000 : nb2d = 64;

• Default: 0

lmaxmax

• Type: Integer

• Description: If not equals to 2, then the maximum l channels on LCAO is set to lmaxmax. If 2, then the number of l channels will be read from the LCAO data sets. Normally no input should be supplied for this variable so that it is kept as its default.

• Default: 2.

lcao_ecut

• Type: Real

• Description: Energy cutoff (in Ry) for two-center integrals in LCAO. The two-center integration table are obtained via a k space integral whose upper limit is about sqrt(lcao_ecut).

• Default: ecutwfc

lcao_dk

• Type: Real

• Description: k spacing (in Bohr\({}^{-1}\)) for two-center integrals. The two-center integration table are obtained via a k space integral on a uniform grid with spacing lcao_dk.

• Default: 0.01

lcao_dr

• Type: Real

• Description: r spacing (in Bohr) of the integration table of two-center integrals.

• Default: 0.01

lcao_rmax

• Type: Real

• Description: Maximum distance (in Bohr) for the two-center integration table.

• Default: 30

search_radius

• Type: Real

• Description: Searching radius in finding the neighbouring atoms. By default the radius will be automatically determined by the cutoffs of orbitals and nonlocal beta projectors.

• Default: -1

• Unit: Bohr

search_pbc

• Type: Boolean

• Description: If True, periodic images will be included in searching for the neighbouring atoms. If False, periodic images will be ignored.

• Default: True

bx, by, bz

• Type: Integer

• Description: In the matrix operation of grid integral, bx/by/bz grids (in x, y, z directions) are treated as a whole as a matrix element. A different value will affect the calculation speed. The default is 0, which means abacus will automatically calculate these values.

• Default: 0

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Electronic structure

These variables are used to control the electronic structure and geometry relaxation calculations.

basis_type

• Type: String

• Description: Choose the basis set.

  • pw: Using plane-wave basis set only.

  • lcao: Using localized atomic orbital sets.

  • lcao_in_pw: (Unavailable currently, it will be fixed in future versions) Expand the localized atomic set in plane-wave basis.

• Default: pw

ks_solver

• Type: String

• Description: Choose the diagonalization methods for the Hamiltonian matrix expanded in a certain basis set.

  For plane-wave basis,

  • cg: cg method.

  • bpcg: bpcg method, which is a block-parallel Conjugate Gradient (CG) method, typically exhibits higher acceleration in a GPU environment.

  • dav: the Davidson algorithm.

  For atomic orbitals basis,

  • genelpa: This method should be used if you choose localized orbitals.

  • scalapack_gvx: Scalapack can also be used for localized orbitals.

  • cusolver: (Unavailable currently, it will be fixed in future versions) This method needs building with the cusolver component for lcao and at least one gpu is available.

  If you set ks_solver=genelpa for basis_type=pw, the program will be stopped with an error message:

  genelpa can not be used with plane wave basis.
  

  Then the user has to correct the input file and restart the calculation.

• Default: cg (plane-wave basis), or genelpa (localized atomic orbital basis, if compiling option USE_ELPA has been set), scalapack_gvx, (localized atomic orbital basis, if compiling option USE_ELPA has not been set)

nbands

• Type: Integer

• Description: The number of Kohn-Sham orbitals to calculate. It is recommended to setup this value, especially when smearing techniques are utilized, more bands should be included.

• Default:

  • nspin=1: max(1.2*occupied_bands, occupied_bands + 10)

  • nspin=2: max(1.2*nelec_spin, nelec_spin + 10), in which nelec_spin = max(nelec_spin_up, nelec_spin_down)

  • nspin=4: max(1.2*nelec, nelec + 20)

nbands_istate

• Type: Integer

• Availability: Only used when calculation = get_wf or calculation = get_pchg.

• Description: The number of bands around the Fermi level you would like to calculate. get_wf means to calculate the envelope functions of wave functions \(\Psi_{i}=\Sigma_{\mu}C_{i\mu}\Phi_{\mu}\), where \(\Psi_{i}\) is the ith wave function with the band index \(i\) and \(\Phi_{\mu}\) is the localized atomic orbital set. get_pchg means to calculate the density of each wave function \(|\Psi_{i}|^{2}\). Specifically, suppose we have highest occupied bands at 100th wave functions. And if you set this variable to 5, it will print five wave functions from 96th to 105th. But before all this can be carried out, the wave functions coefficients should be first calculated and written into a file by setting the flag out_wfc_lcao = 1.

• Default: 5

nspin

• Type: Integer

• Description: The number of spin components of wave functions.

  • 1: Spin degeneracy

  • 2: Collinear spin polarized.

  • 4: For the case of noncollinear polarized, nspin will be automatically set to 4 without being specified by the user.

• Default: 1

smearing_method

• Type: String

• Description: It indicates which occupation and smearing method is used in the calculation.

  • fixed: fixed occupations (available for non-coductors only)

  • gauss or gaussian: Gaussian smearing method.

  • mp: methfessel-paxton smearing method; recommended for metals.

  • fd: Fermi-Dirac smearing method: \(f=1/\{1+\exp[(E-\mu)/kT]\}\) and smearing_sigma below is the temperature \(T\) (in Ry).

• Default: fixed

smearing_sigma

• Type: Real

• Description: Energy range for smearing.

• Default: 0.001

• Unit: Ry

smearing_sigma_temp

• Type: Real

• Description: Energy range for smearing, smearing_sigma = 1/2 * kB * smearing_sigma_temp.

• Default: 2 * smearing_sigma / kB.

• Unit: K

mixing_type

• Type: String

• Availability: smearing_method is not fixed.

• Description: Charge mixing methods.

  • plain: Just simple mixing.

  • pulay: Standard Pulay method. P. Pulay Chemical Physics Letters, (1980)

  • broyden: Simplified modified Broyden method. D.D. Johnson Physical Review B (1988)

  In general, the convergence of the Broyden method is slightly faster than that of the Pulay method.

• Default: broyden

mixing_beta

• Type: Real

• Description: In general, the formula of charge mixing can be written as \(\rho_{new} = \rho_{old} + \beta * \rho_{update}\), where \(\rho_{new}\) represents the new charge density after charge mixing, \(\rho_{old}\) represents the charge density in previous step, \(\rho_{update}\) is obtained through various mixing methods, and \(\beta\) is set by the parameter mixing_beta. A lower value of ‘mixing_beta’ results in less influence of \(\rho_{update}\) on \(\rho_{new}\), making the self-consistent field (SCF) calculation more stable. However, it may require more steps to achieve convergence. We recommend the following options:

  • 0.8: nspin=1

  • 0.4: nspin=2

  • 0.2: nspin=4

  • 0: keep charge density unchanged, usually used for restarting with init_chg=file or testing.

  • 0.1 or less: if convergence of SCF calculation is difficult to reach, please try 0 < mixing_beta < 0.1.

  Note: For low-dimensional large systems, the setup of mixing_beta=0.1, mixing_ndim=20, and mixing_gg0=1.0 usually works well.

• Default: 0.8 for nspin=1, 0.4 for nspin=2, 0.2 for nspin=4.

mixing_beta_mag

• Type: Real

• Description: Mixing parameter of magnetic density.

• Default: 4*mixing_beta

mixing_ndim

• Type: Integer

• Description: It indicates the mixing dimensions in Pulay or Broyden. Pulay and Broyden method use the density from previous mixing_ndim steps and do a charge mixing based on this density.

  For systems that are difficult to converge, one could try increasing the value of ‘mixing_ndim’ to enhance the stability of the self-consistent field (SCF) calculation.

• Default: 8

mixing_gg0

• Type: Real

• Description: Whether to perfom Kerker scaling for charge density.

  • >0: The high frequency wave vectors will be suppressed by multiplying a scaling factor \(\frac{k^2}{k^2+gg0^2}\). Setting mixing_gg0 = 1.0 is normally a good starting point. Kerker preconditioner will be automatically turned off if mixing_beta <= 0.1.

  • 0: No Kerker scaling is performed.

  For systems that are difficult to converge, particularly metallic systems, enabling Kerker scaling may aid in achieving convergence.

• Default: 1.0

mixing_gg0_mag

• Type: Real

• Description: Whether to perfom Kerker preconditioner of magnetic density. Note: we do not recommand to open Kerker preconditioner of magnetic density unless the system is too hard to converge.

• Default: 0.0

mixing_tau

• Type: Boolean

• Availability: Only relevant for meta-GGA calculations.

• Description: Whether to mix the kinetic energy density.

  • True: The kinetic energy density will also be mixed. It seems for general cases, SCF converges fine even without this mixing. However, if there is difficulty in converging SCF for meta-GGA, it might be helpful to turn this on.

  • False: The kinetic energy density will not be mixed.

• Default: False

mixing_dftu

• Type: Boolean

• Availability: Only relevant for DFT+U calculations.

• Description: Whether to mix the occupation matrices.

  • True: The occupation matrices will also be mixed by plain mixing. From experience this is not very helpful if the +U calculation does not converge.

  • False: The occupation matrices will not be mixed.

• Default: False

gamma_only

• Type: Integer

• Availability: Only used in localized orbitals set

• Description: Whether to use gamma_only algorithm.

  • 0: more than one k-point is used and the ABACUS is slower compared to the gamma only algorithm.

  • 1: ABACUS uses gamma only, the algorithm is faster and you don’t need to specify the k-points file.

  Note: If gamma_only is set to 1, the KPT file will be overwritten. So make sure to turn off gamma_only for multi-k calculations.

• Default: 0

printe

• Type: Integer

• Description: Print out energy for each band for every printe step

• Default: 100

scf_nmax

• Type: Integer

• Description: This variable indicates the maximal iteration number for electronic iterations.

• Default: 100

scf_thr

• Type: Real

• Description: It’s the threshold for electronic iteration. It represents the charge density error between two sequential densities from electronic iterations. Usually for local orbitals, usually 1e-6 may be accurate enough.

• Default: 1.0e-9 (plane-wave basis), or 1.0e-7 (localized atomic orbital basis).

scf_thr_type

• Type: Integer

• Description: Choose the calculation method of convergence criterion.

  • 1: the criterion is defined as \(\Delta\rho_G = \frac{1}{2}\iint{\frac{\Delta\rho(r)\Delta\rho(r')}{|r-r'|}d^3r d^3r'}\).

  • 2: the criterion is defined as \(\Delta\rho_R = \int{|\Delta\rho(r)|d^3r}\).

  Note: This parameter is still under testing and the default setting is usually sufficient.

• Default: 1 (plane-wave basis), or 2 (localized atomic orbital basis).

chg_extrap

• Type: String

• Description: Methods to do extrapolation of density when ABACUS is doing geometry relaxations or molecular dynamics.

  • atomic: atomic extrapolation.

  • first-order: first-order extrapolation.

  • second-order: second-order extrapolation.

• Default: first-order (geometry relaxations), second-order (molecular dynamics), else atomic

lspinorb

• Type: Boolean

• Description: Whether to consider spin-orbital coupling effect in the calculation.

  • True: Consider spin-orbital coupling effect, and nspin is also automatically set to 4.

  • False: Do not consider spin-orbital coupling effect.

• Default: False

noncolin

• Type: Boolean

• Description: Whether to allow non-collinear polarization, in which case the coupling between spin up and spin down will be taken into account.

  • True: Allow non-collinear polarization, and nspin is also automatically set to 4.

  • False: Do not allow non-collinear polarization.

• Default: False

soc_lambda

• Type: Real

• Availability: Relevant for soc calculations.

• Description: Sometimes, for some real materials, both scalar-relativistic and full-relativistic can not describe the exact spin-orbit coupling. Artificial modulation may help in such cases.

  soc_lambda, which has value range [0.0, 1.0] , is used for modulate SOC effect.

  In particular, soc_lambda 0.0 refers to scalar-relativistic case and soc_lambda 1.0 refers to full-relativistic case.

• Default: 1.0

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Electronic structure (SDFT)

These variables are used to control the parameters of stochastic DFT (SDFT), mix stochastic-deterministic DFT (MDFT), or complete-basis Chebyshev method (CT). In the following text, stochastic DFT is used to refer to these three methods. We suggest using SDFT to calculate high-temperature systems and we only support smearing_method “fd”. Both “scf” and “nscf” calculation are supported.

method_sto

• Type: Integer

• Availability: esolver_type = sdft

• Description: Different methods to do stochastic DFT

  • 1: Calculate \(T_n(\hat{h})\ket{\chi}\) twice, where \(T_n(x)\) is the n-th order Chebyshev polynomial and \(\hat{h}=\frac{\hat{H}-\bar{E}}{\Delta E}\) owning eigenvalues \(\in(-1,1)\). This method cost less memory but is slower.

  • 2: Calculate \(T_n(\hat{h})\ket{\chi}\) once but needs much more memory. This method is much faster. Besides, it calculates \(N_e\) with \(\bra{\chi}\sqrt{\hat f}\sqrt{\hat f}\ket{\chi}\), which needs a smaller nche_sto. However, when the memory is not enough, only method 1 can be used.

  • other: use 2

• Default: 2

nbands_sto

• Type: Integer or string

• Availability: esolver_type = sdft

• Description: The number of stochastic orbitals

  • > 0: Perform stochastic DFT. Increasing the number of bands improves accuracy and reduces stochastic errors, which scale as \(1/\sqrt{N_{\chi}}\); To perform mixed stochastic-deterministic DFT, you should set nbands, which represents the number of KS orbitals.

  • 0: Perform Kohn-Sham DFT.

  • all: All complete basis sets are used to replace stochastic orbitals with the Chebyshev method (CT), resulting in the same results as KSDFT without stochastic errors.

• Default: 256

nche_sto

• Type: Integer

• Availability: esolver_type = sdft

• Description: Chebyshev expansion orders for stochastic DFT.

• Default: 100

emin_sto

• Type: Real

• Availability: esolver_type = sdft

• Description: Trial energy to guess the lower bound of eigen energies of the Hamiltonian Operator \(\hat{H}\).

• Default: 0.0

• Unit: Ry

emax_sto

• Type: Real

• Availability: esolver_type = sdft

• Description: Trial energy to guess the upper bound of eigen energies of the Hamiltonian Operator \(\hat{H}\).

• Default: 0.0

• Unit: Ry

seed_sto

• Type: Integer

• Availability: esolver_type = sdft

• Description: The random seed to generate stochastic orbitals.

  • >= 0: Stochastic orbitals have the form of \(\exp(i2\pi\theta(G))\), where \(\theta\) is a uniform distribution in \((0,1)\).

  • 0: the seed is decided by time(NULL).

  • <= -1: Stochastic orbitals have the form of \(\pm1\) with equal probability.

  • -1: the seed is decided by time(NULL).

• Default: 0

initsto_ecut

• Type: Real

• Availability: esolver_type = sdft

• Description: Stochastic wave functions are initialized in a large box generated by “4*initsto_ecut”. initsto_ecut should be larger than ecutwfc. In this method, SDFT results are the same when using different cores. Besides, coefficients of the same G are the same when ecutwfc is rising to initsto_ecut. If it is smaller than ecutwfc, it will be turned off.

• Default: 0.0

• Unit: Ry

initsto_freq

• Type: Integer

• Availability: esolver_type = sdft

• Description: Frequency (once each initsto_freq steps) to generate new stochastic orbitals when running md.

  • positive integer: Update stochastic orbitals

  • 0: Never change stochastic orbitals.

• Default: 0

npart_sto

• Type: Integer

• Availability: method_sto = 2 and out_dos = True or cal_cond = True

• Description: Make memory cost to 1/npart_sto times of the previous one when running the post process of SDFT like DOS or conductivities.

• Default: 1

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Geometry relaxation

These variables are used to control the geometry relaxation.

relax_method

• Type: String

• Description: The methods to do geometry optimization.

  • cg: using the conjugate gradient (CG) algorithm. Note that there are two implementations of the conjugate gradient (CG) method, see relax_new.

  • bfgs: using the Broyden–Fletcher–Goldfarb–Shanno (BFGS) algorithm.

  • cg_bfgs: using the CG method for the initial steps, and switching to BFGS method when the force convergence is smaller than relax_cg_thr.

  • sd: using the steepest descent (SD) algorithm.

  • fire: the Fast Inertial Relaxation Engine method (FIRE), a kind of molecular-dynamics-based relaxation algorithm, is implemented in the molecular dynamics (MD) module. The algorithm can be used by setting calculation to md and md_type to fire. Also ionic velocities should be set in this case. See fire for more details.

• Default: cg

relax_new

• Type: Boolean

• Description: At around the end of 2022 we made a new implementation of the Conjugate Gradient (CG) method for relax and cell-relax calculations. But the old implementation was also kept.

  • True: use the new implementation of CG method for relax and cell-relax calculations.

  • False: use the old implementation of CG method for relax and cell-relax calculations.

• Default: True

relax_scale_force

• Type: Real

• Availability: only used when relax_new set to True

• Description: The paramether controls the size of the first conjugate gradient step. A smaller value means the first step along a new CG direction is smaller. This might be helpful for large systems, where it is safer to take a smaller initial step to prevent the collapse of the whole configuration.

• Default: 0.5

relax_nmax

• Type: Integer

• Description: The maximal number of ionic iteration steps, the minimum value is 1.

• Default: 1

relax_cg_thr

• Type: Real

• Description: When move-method is set to cg_bfgs, a mixed algorithm of conjugate gradient (CG) method and Broyden–Fletcher–Goldfarb–Shanno (BFGS) method is used. The ions first move according to CG method, then switched to BFGS method when the maximum of force on atoms is reduced below the CG force threshold, which is set by this parameter.

• Default: 0.5

• Unit: eV/Angstrom

cal_force

• Type: Boolean

• Description:

  • True calculate the force at the end of the electronic iteration

  • False no force calculation at the end of the electronic iteration

• Default: False if calculation is set to scf, True if calculation is set to cell-relax, relax, or md.

force_thr

• Type: Real

• Description: Threshold of the force convergence in Ry/Bohr. The threshold is compared with the largest force among all of the atoms. The recommended value for using atomic orbitals is 0.04 eV/Angstrom (0.0016 Ry/Bohr). The parameter is equivalent to force_thr_ev except for the unit. You may choose either you like.

• Default: 0.001

• Unit: Ry/Bohr (25.7112 eV/Angstrom)

force_thr_ev

• Type: Real

• Description: Threshold of the force convergence in eV/Angstrom. The threshold is compared with the largest force among all of the atoms. The recommended value for using atomic orbitals is 0.04 eV/Angstrom (0.0016 Ry/Bohr). The parameter is equivalent to force_thr except for the unit. You may choose either you like.

• Default: 0.0257112

• Unit: eV/Angstrom (0.03889 Ry/Bohr)

force_thr_ev2

• Type: Real

• Description: The calculated force will be set to 0 when it is smaller than the parameter force_thr_ev2.

• Default: 0.0

• Unit: eV/Angstrom

relax_bfgs_w1

• Type: Real

• Description: This variable controls the Wolfe condition for Broyden–Fletcher–Goldfarb–Shanno (BFGS) algorithm used in geometry relaxation. You can look into the paper Phys.Chem.Chem.Phys.,2000,2,2177 for more information.

• Default: 0.01

relax_bfgs_w2

• Type: Real

• Description: This variable controls the Wolfe condition for Broyden–Fletcher–Goldfarb–Shanno (BFGS) algorithm used in geometry relaxation. You can look into the paper Phys.Chem.Chem.Phys.,2000,2,2177 for more information.

• Default: 0.5

relax_bfgs_rmax

• Type: Real

• Description: This variable is for geometry optimization. It stands for the maximal movement of all the atoms. The sum of the movements from all atoms can be increased during the optimization steps. However, it can not be larger than relax_bfgs_rmax

• Unit: Bohr

• Default: 0.8

relax_bfgs_rmin

• Type: Real

• Description: This variable is for geometry optimization. It indicates the minimal movement of all the atoms. When the movement of all the atoms is smaller than relax_bfgs_rmin Bohr, and the force convergence is still not achieved, the calculation will break down.

• Default: 1e-5

• Unit: Bohr

relax_bfgs_init

• Type: Real

• Description: This variable is for geometry optimization. It stands for the sum of initial movements of all of the atoms.

• Default: 0.5

• Unit: Bohr

cal_stress

• Type: Boolean

• Description:

  • True: calculate the stress at the end of the electronic iteration

  • False: no calculation of the stress at the end of the electronic iteration

• Default: True if calculation is cell-relax, False otherwise.

stress_thr

• Type: Real

• Description: The threshold of the stress convergence. The threshold is compared with the largest component of the stress tensor.

• Default: 0.5

• Unit: kbar

press1, press2, press3

• Type: Real

• Description: The external pressures along three axes. Positive input value is taken as compressive stress.

• Default: 0

• Unit: kbar

fixed_axes

• Type: String

• Availability: only used when calculation set to cell-relax

• Description: Axes that are fixed during cell relaxation. Possible choices are:

  • None: default; all of the axes can relax

  • volume: relaxation with fixed volume

  • shape: fix shape but change volume (i.e. only lattice constant changes)

  • a: fix a axis during relaxation

  • b: fix b axis during relaxation

  • c: fix c axis during relaxation

  • ab: fix both a and b axes during relaxation

  • ac: fix both a and c axes during relaxation

  • bc: fix both b and c axes during relaxation

Note : fixed_axes = “shape” and “volume” are only available for relax_new = True

• Default: None

fixed_ibrav

• Type: Boolean

• Availability: Must be used along with relax_new set to True, and a specific latname must be provided

• Description:

  • True: the lattice type will be preserved during relaxation

  • False: No restrictions are exerted during relaxation in terms of lattice type

Note: it is possible to use fixed_ibrav with fixed_axes, but please make sure you know what you are doing. For example, if we are doing relaxation of a simple cubic lattice (latname = “sc”), and we use fixed_ibrav along with fixed_axes = “volume”, then the cell is never allowed to move and as a result, the relaxation never converges.

• Default: False

fixed_atoms

• Type: Boolean

• Description:

  • True: The direct coordinates of atoms will be preserved during variable-cell relaxation.

  • False: No restrictions are exerted on positions of all atoms. However, users can still fix certain components of certain atoms by using the m keyword in STRU file. For the latter option, check the end of this instruction.

• Default: False

cell_factor

• Type: Real

• Description: Used in the construction of the pseudopotential tables. It should exceed the maximum linear contraction of the cell during a simulation.

• Default: 1.2

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Variables related to output information

These variables are used to control the output of properties.

out_mul

• Type: Boolean

• Availability: Numerical atomic orbital basis

• Description: Whether to print the Mulliken population analysis result into OUT.${suffix}/mulliken.txt. In molecular dynamics calculations, the output frequency is controlled by out_interval.

• Default: False

out_freq_elec

• Type: Integer

• Description: The output frequency of the charge density (controlled by out_chg), wavefunction (controlled by out_wfc_pw or out_wfc_r), and density matrix of localized orbitals (controlled by out_dm).

  • >0: Output them every out_freq_elec iteration numbers in electronic iterations.

  • 0: Output them when the electronic iteration is converged or reaches the maximal iteration number.

• Default: 0

out_chg

• Type: Boolean

• Description: Whether to output the charge density (in Bohr^-3) on real space grids into the density files in the folder OUT.${suffix}. The files are named as:

  • npsin = 1: SPIN1_CHG.cube;

  • npsin = 2: SPIN1_CHG.cube, and SPIN2_CHG.cube;

  • npsin = 4: SPIN1_CHG.cube, SPIN2_CHG.cube, SPIN3_CHG.cube, and SPIN4_CHG.cube.

  The circle order of the charge density on real space grids is: x is the outer loop, then y and finally z (z is moving fastest).

• Default: False

out_pot

• Type: Integer

• Description:

  • 1: Output the total local potential (i.e., local pseudopotential + Hartree potential + XC potential + external electric field (if exists) + dipole correction potential (if exists) + …) on real space grids (in Ry) into files in the folder OUT.${suffix}. The files are named as:

    • npsin = 1: SPIN1_POT.cube;

    • npsin = 2: SPIN1_POT.cube, and SPIN2_POT.cube;

    • npsin = 4: SPIN1_POT.cube, SPIN2_POT.cube, SPIN3_POT.cube, and SPIN4_POT.cube.

  • 2: Output the electrostatic potential on real space grids into OUT.${suffix}/ElecStaticPot.cube. The Python script named tools/average_pot/aveElecStatPot.py can be used to calculate the average electrostatic potential along the z-axis and outputs it into ElecStaticPot_AVE.

    Please note that the total local potential refers to the local component of the self-consistent potential, excluding the non-local pseudopotential. The distinction between the local potential and the electrostatic potential is as follows: local potential = electrostatic potential + XC potential.

• Default: 0

out_dm

• Type: Boolean

• Availability: Numerical atomic orbital basis (gamma-only algorithm)

• Description: Whether to output the density matrix of localized orbitals into files in the folder OUT.${suffix}. The files are named as:

  • npsin = 1: SPIN1_DM;

  • npsin = 2: SPIN1_DM, and SPIN2_DM.

• Default: False

out_dm1

• Type: Boolean

• Availability: Numerical atomic orbital basis (multi-k points)

• Description: Whether to output the density matrix of localized orbitals into files in the folder OUT.${suffix}. The density matrices are written in the format of sparse matrices, as mentioned in out_mat_hs2. The files are named as:

  • npsin = 1: data-DMR-sparse_SPIN0.csr;

  • npsin = 2: data-DMR-sparse_SPIN0.csr, and data-DMR-sparse_SPIN1.csr.

• Default: False

out_wfc_pw

• Type: Integer

• Availability: Plane wave basis or get_wf calculation in numerical atomic orbital basis

• Description:

  • 1: Output the coefficients of wave functions into text files named OUT.${suffix}/WAVEFUNC${K}.txt, where ${K} is the index of k points.

  • 2: results are stored in binary files named OUT.${suffix}/WAVEFUNC${K}.dat.

• Default: 0

out_wfc_r

• Type: Boolean

• Availability: Plane wave basis or get_wf calculation in numerical atomic orbital basis

• Description: Whether to output real-space wave functions into OUT.suffix/wfc_realspace/wfc_realspace_${K}_${B}, where ${K} is the index of k points, ${B} is the index of bands.

• Default: False

out_wfc_lcao

• Type: Integer

• Availability: Numerical atomic orbital basis

• Description: Whether to output the wavefunction coefficients into files in the folder OUT.${suffix}. The files are named as:

  • 0: no output

  • 1: (txt format)

    • gamma-only: LOWF_GAMMA_S1.txt;

    • non-gamma-only: LOWF_K_${k}.txt, where ${k} is the index of k points.

  • 2: (binary format)

    • gamma-only: LOWF_GAMMA_S1.dat;

    • non-gamma-only: LOWF_K_${k}.dat, where ${k} is the index of k points.

  The corresponding sequence of the orbitals can be seen in Basis Set.

  Also controled by out_interval and out_app_flag.

• Default: Flase

out_dos

• Type: Boolean

• Description: Whether to output the density of states (DOS). For more information, refer to the dos.md.

• Default: False

out_band

• Type: Boolean

• Description: Whether to output the band structure (in eV). For more information, refer to the band.md

• Default: False

out_proj_band

• Type: Boolean

• Description: Whether to output the projected band structure. For more information, refer to the band.md

• Default: False

out_stru

• Type: Boolean

• Description: Whether to output structure files per ionic step in geometry relaxation calculations into OUT.${suffix}/STRU_ION${istep}_D, where ${istep} is the ionic step.

• Default: False

out_bandgap

• Type: Boolean

• Description: Whether to print the bandgap per electronic iteration into OUT.${suffix}/running_${calculation}.log. The value of bandgaps can be obtained by searching for the keyword:

  • nupdown > 0: E_bandgap_up and E_bandgap_dw

  • nupdown = 0: E_bandgap

• Default: False

out_level

• Type: String

• Description: Control the output level of information in OUT.${suffix}/running_${calculation}.log.

  • ie: electronic iteration level, which prints useful information for electronic iterations;

  • i: geometry relaxation level, which prints some information for geometry relaxations additionally;

  • m: molecular dynamics level, which does not print some information for simplicity.

• Default: ie

out_alllog

• Type: Boolean

• Description: Whether to print information into individual logs from all ranks in an MPI run.

  • True: Information from each rank will be written into individual files named OUT.${suffix}/running_${calculation}_${rank+1}.log.

  • False: Information will only be written from rank 0 into a file named OUT.${suffix}/running_${calculation}.log.

• Default: False

out_mat_hs

• Type: Boolean

• Availability: Numerical atomic orbital basis

• Description: Whether to print the upper triangular part of the Hamiltonian matrices (in Ry) and overlap matrices for each k point into files in the directory OUT.${suffix}. For more information, please refer to hs_matrix.md. Also controled by out_interval and out_app_flag.

• Default: False

out_mat_r

• Type: Boolean

• Availability: Numerical atomic orbital basis (not gamma-only algorithm)

• Description: Whether to print the matrix representation of the position matrix (in Bohr) into a file named data-rR-tr in the directory OUT.${suffix}. For more information, please refer to position_matrix.md.

• Default: False

out_mat_hs2

• Type: Boolean

• Availability: Numerical atomic orbital basis (not gamma-only algorithm)

• Description: Whether to print files containing the Hamiltonian matrix \(H(R)\) (in Ry) and overlap matrix \(S(R)\) into files in the directory OUT.${suffix}. For more information, please refer to hs_matrix.md.

• Default: False

out_mat_t

• Type: Boolean

• Availability: Numerical atomic orbital basis (not gamma-only algorithm)

• Description: For LCAO calculations, if out_mat_t is set to 1, ABACUS will generate files containing the kinetic energy matrix \(T(R)\) (in Ry). The format will be the same as the Hamiltonian matrix \(H(R)\) and overlap matrix \(S(R)\) as mentioned in out_mat_hs2. The name of the files will be data-TR-sparse_SPIN0.csr and so on. Also controled by out_interval and out_app_flag.

• Default: False

out_mat_dh

• Type: Boolean

• Availability: Numerical atomic orbital basis (not gamma-only algorithm)

• Description: Whether to print files containing the derivatives of the Hamiltonian matrix (in Ry/Bohr). The format will be the same as the Hamiltonian matrix \(H(R)\) and overlap matrix \(S(R)\) as mentioned in out_mat_hs2. The name of the files will be data-dHRx-sparse_SPIN0.csr and so on. Also controled by out_interval and out_app_flag.

• Default: False

out_app_flag

• Type: Boolean

• Availability: Numerical atomic orbital basis (not gamma-only algorithm)

• Description: Whether to output \(r(R)\), \(H(R)\), \(S(R)\), \(T(R)\), \(dH(R)\), \(H(k)\), \(S(k)\) and \(wfc(k)\) matrices in an append manner during molecular dynamics calculations. Check input parameters out_mat_r, out_mat_hs2, out_mat_t, out_mat_dh, out_mat_hs and out_wfc_lcao for more information.

• Default: true

out_interval

• Type: Integer

• Availability: Numerical atomic orbital basis

• Description: Control the interval for printing Mulliken population analysis, \(r(R)\), \(H(R)\), \(S(R)\), \(T(R)\), \(dH(R)\), \(H(k)\), \(S(k)\) and \(wfc(k)\) matrices during molecular dynamics calculations. Check input parameters out_mul, out_mat_r, out_mat_hs2, out_mat_t, out_mat_dh, out_mat_hs and out_wfc_lcao for more information, respectively.

• Default: 1

out_element_info

• Type: Boolean

• Description: Whether to print element information into files in the directory OUT.${suffix}/${element_label}, including pseudopotential and orbital information of the element (in atomic Ryberg units).

• Default: False

restart_save

• Type: Boolean

• Availability: Numerical atomic orbital basis

• Description: Whether to save charge density files and Hamiltonian matrix files per ionic step, which are used to restart calculations. According to the value of read_file_dir:

  • auto: These files are saved in folder OUT.${suffix}/restart/;

  • other: These files are saved in folder ${read_file_dir}/restart/.

• Default: False

restart_load

• Type: Boolean

• Availability: Numerical atomic orbital basis

• Description: If restart_save is set to true and an electronic iteration is finished, calculations can be restarted from the charge density file and Hamiltonian matrix file, which are saved in the former calculation. Please ensure read_file_dir is correct, and the charge density file and Hamiltonian matrix file exist.

• Default: False

rpa

• Type: Boolean

• Description: Generate output files used in rpa calculations.

• Default: False

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Density of states

These variables are used to control the calculation of DOS. Detailed introduction

dos_edelta_ev

• Type: Real

• Description: the step size in writing Density of States (DOS)

• Default: 0.01

• Unit: eV

dos_sigma

• Type: Real

• Description: the width of the Gaussian factor when obtaining smeared Density of States (DOS)

• Default: 0.07

• Unit: eV

dos_scale

• Type: Real

• Description: Defines the energy range of DOS output as (emax-emin)*(1+dos_scale), centered at (emax+emin)/2. This parameter will be used when dos_emin and dos_emax are not set.

• Default: 0.01

• Unit: eV

dos_emin_ev

• Type: Real

• Description: the minimal range for Density of States (DOS)

  • If set, “dos_scale” will be ignored.

• Default: Minimal eigenenergy of \(\hat{H}\)

• Unit: eV

dos_emax_ev

• Type: Real

• Description: the maximal range for Density of States (DOS)

  • If set, “dos_scale” will be ignored.

• Default: Maximal eigenenergy of \(\hat{H}\)

• Unit: eV

dos_nche

• Type: Integer The order of Chebyshev expansions when using Stochastic Density Functional Theory (SDFT) to calculate DOS.

• Default: 100

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NAOs

These variables are used to control the generation of numerical atomic orbitals (NAOs), whose radial parts are linear combinations of spherical Bessel functions with a node (i.e., evaluate to zero) at the cutoff radius. In plane-wave-based calculations, necessary information will be printed into OUT.${suffix}/orb_matrix.${i}.dat, which serves as an input file for the generation of NAOs. Please check SIAB package for more information.

bessel_nao_ecut

• Type: Real

• Description: “Energy cutoff” (in Ry) of spherical Bessel functions. The number of spherical Bessel functions that constitute the radial parts of NAOs is determined by sqrt(bessel_nao_ecut)\(\times\)bessel_nao_rcut/\(\pi\).

• Default: ecutwfc

bessel_nao_tolerence

• Type: Real

• Description: tolerance when searching for the zeros of spherical Bessel functions.

• Default: 1.0e-12

bessel_nao_rcut

• Type: Real

• Description: Cutoff radius (in Bohr) and the common node of spherical Bessel functions used to construct the NAOs.

• Default: 6.0

bessel_nao_smooth

• Type: Boolean

• Description: if True, NAOs will be smoothed near the cutoff radius by \(1-\exp\left(-\frac{(r-r_{cut})^2}{2\sigma^2}\right)\). See bessel_nao_rcut for \(r_{cut}\) and bessel_nao_sigma for \(\sigma\).

• Default: True

bessel_nao_sigma

• Type: Real

• Description: Smoothing range (in Bohr). See also bessel_nao_smooth.

• Default: 0.1

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DeePKS

These variables are used to control the usage of DeePKS method (a comprehensive data-driven approach to improve the accuracy of DFT). Warning: this function is not robust enough for the current version. Please try the following variables at your own risk:

deepks_out_labels

• Type: Boolean

• Availability: numerical atomic orbital basis

• Description: print energy and force labels and descriptors for DeePKS training

• Note: In LCAO calculation, the path of a numerical descriptor (an orb file) is needed to be specified under the NUMERICAL_DESCRIPTOR tag in the STRU file. For example:

  NUMERICAL_ORBITAL
  H_gga_8au_60Ry_2s1p.orb
  O_gga_7au_60Ry_2s2p1d.orb
  
  NUMERICAL_DESCRIPTOR
  jle.orb
  

• Default: False

deepks_scf

• Type: Boolean

• Availability: numerical atomic orbital basis

• Description: perform self-consistent field iteration in DeePKS method

• Note: A trained, traced model file is needed.

• Default: False

deepks_model

• Type: String

• Availability: numerical atomic orbital basis and deepks_scf is true

• Description: the path of the trained, traced neural network model file generated by deepks-kit

• Default: None

bessel_descriptor_lmax

• Type: Integer

• Availability: gen_bessel calculation

• Description: the maximum angular momentum of the Bessel functions generated as the projectors in DeePKS

• NOte: To generate such projectors, set calculation type to gen_bessel in ABACUS. See also calculation.

• Default: 2

bessel_descriptor_ecut

• Type: Real

• Availability: gen_bessel calculation

• Description: energy cutoff of Bessel functions

• Default: same as ecutwfc

• Unit: Ry

bessel_descriptor_tolerence

• Type: Real

• Availability: gen_bessel calculation

• Description: tolerance for searching the zeros of Bessel functions

• Default: 1.0e-12

bessel_descriptor_rcut

• Type: Real

• Availability: gen_bessel calculation

• Description: cutoff radius of Bessel functions

• Default: 6.0

• Unit: Bohr

bessel_descriptor_smooth

• Type: Boolean

• Availability: gen_bessel calculation

• Description: smooth the Bessel functions at radius cutoff

• Default: False

bessel_descriptor_sigma

• Type: Real

• Availability: gen_bessel calculation

• Description: smooth parameter at the cutoff radius of projectors

• Default: 0.1

• Unit: Bohr

deepks_bandgap

• Type: Boolean

• Availability: numerical atomic orbital basis and deepks_scf is true

• Description: include bandgap label for DeePKS training

• Default: False

deepks_out_unittest

• Type: Boolean

• Description: generate files for constructing DeePKS unit test

• Note: Not relevant when running actual calculations. When set to 1, ABACUS needs to be run with only 1 process.

• Default: False

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OFDFT: orbital free density functional theory

of_kinetic

• Type: String

• Availability: OFDFT

• Description: The type of KEDF (kinetic energy density functional).

  • wt: Wang-Teter.

  • tf: Thomas-Fermi.

  • vw: von Weizsäcker.

  • tf+: TF\(\rm{\lambda}\)vW, the parameter \(\rm{\lambda}\) can be set by of_vw_weight.

  • lkt: Luo-Karasiev-Trickey.

• Default: wt

of_method

• Type: String

• Availability: OFDFT

• Description: The optimization method used in OFDFT.

  • cg1: Polak-Ribiere. Standard CG algorithm.

  • cg2: Hager-Zhang (generally faster than cg1).

  • tn: Truncated Newton algorithm.

• Default:tn

of_conv

• Type: String

• Availability: OFDFT

• Description: Criterion used to check the convergence of OFDFT.

  • energy: Ttotal energy changes less than of_tole.

  • potential: The norm of potential is less than of_tolp.

  • both: Both energy and potential must satisfy the convergence criterion.

• Default: energy

of_tole

• Type: Real

• Availability: OFDFT

• Description: Tolerance of the energy change for determining the convergence.

• Default: 2e-6

• Unit: Ry

of_tolp

• Type: Real

• Availability: OFDFT

• Description: Tolerance of potential for determining the convergence.

• Default: 1e-5

• Unit: Ry

of_tf_weight

• Type: Real

• Availability: OFDFT with of_kinetic=tf, tf+, wt

• Description: Weight of TF KEDF (kinetic energy density functional).

• Default: 1.0

of_vw_weight

• Type: Real

• Availability: OFDFT with of_kinetic=vw, tf+, wt, lkt

• Description: Weight of vW KEDF (kinetic energy density functional).

• Default: 1.0

of_wt_alpha

• Type: Real

• Availability: OFDFT with of_kinetic=wt

• Description: Parameter alpha of WT KEDF (kinetic energy density functional).

• Default: \(5/6\)

of_wt_beta

• Type: Real

• Availability: OFDFT with of_kinetic=wt

• Description: Parameter beta of WT KEDF (kinetic energy density functional).

• Default: \(5/6\)

of_wt_rho0

• Type: Real

• Availability: OFDFT with of_kinetic=wt

• Description: The average density of system.

• Default: 0.0

• Unit: Bohr^-3

of_hold_rho0

• Type: Boolean

• Availability: OFDFT with of_kinetic=wt

• Description: Whether to fix the average density rho0.

  • True: rho0 will be fixed even if the volume of system has changed, it will be set to True automatically if of_wt_rho0 is not zero.

  • False: rho0 will change if volume of system has changed.

• Default: False

of_lkt_a

• Type: Real

• Availability: OFDFT with of_kinetic=lkt

• Description: Parameter a of LKT KEDF (kinetic energy density functional).

• Default: 1.3

of_read_kernel

• Type: Boolean

• Availability: OFDFT with of_kinetic=wt

• Description: Whether to read in the kernel file.

  • True: The kernel of WT KEDF (kinetic energy density functional) will be filled from the file specified by of_kernel_file.

  • False: The kernel of WT KEDF (kinetic energy density functional) will be filled from formula.

• Default: False

of_kernel_file

• Type: String

• Availability: OFDFT with of_read_kernel=True

• Description: The name of WT kernel file.

• Default: WTkernel.txt

of_full_pw

• Type: Boolean

• Availability: OFDFT

• Description: Whether to use full planewaves.

  • True: Ecut will be ignored while collecting planewaves, so that all planewaves will be used in FFT.

  • False: Only use the planewaves inside ecut, the same as KSDFT.

• Default: True

of_full_pw_dim

• Type: Integer

• Availability: OFDFT with of_full_pw = True

• Description: Specify the parity of FFT dimensions.

  • 0: either odd or even.

  • 1: odd only.

  • 2: even only.

  Note: Even dimensions may cause slight errors in FFT. It should be ignorable in ofdft calculation, but it may make Cardinal B-spline interpolation unstable, so please set of_full_pw_dim = 1 if nbspline != -1.

• Default: 0

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Electric field and dipole correction

These variables are relevant to electric field and dipole correction

efield_flag

• Type: Boolean

• Description: added the electric field.

  • True: A saw-like potential simulating an electric field is added to the bare ionic potential.

  • False: Not added the electric field.

• Default: False

dip_cor_flag

• Type: Boolean

• Availability: with dip_cor_flag = True and efield_flag = True.

• Description: Added a dipole correction to the bare ionic potential.

  • True：A dipole correction is also added to the bare ionic potential.

  • False: A dipole correction is not added to the bare ionic potential.

Note: If you want no electric field, parameter efield_amp should be zero. Must be used ONLY in a slab geometry for surface alculations, with the discontinuity FALLING IN THE EMPTY SPACE.

• Default: False

efield_dir

• Type: Integer

• Availability: with efield_flag = True.

• Description: The direction of the electric field or dipole correction is parallel to the reciprocal lattice vector, so the potential is constant in planes defined by FFT grid points, efield_dir can set to 0, 1 or 2.

  • 0: parallel to \(b_1=\frac{2\pi(a_2\times a_3)}{a_1\cdot(a_2\times a_3)}\)

  • 1: parallel to \(b_2=\frac{2\pi(a_3\times a_1)}{a_1\cdot(a_2\times a_3)}\)

  • 2: parallel to \(b_3=\frac{2\pi(a_1\times a_2)}{a_1\cdot(a_2\times a_3)}\)

• Default: 2

efield_pos_max

• Type: Real

• Availability: with efield_flag = True.

• Description: Position of the maximum of the saw-like potential along crystal axis efield_dir, within the unit cell, 0 < efield_pos_max < 1.

• Default: 0.5

efield_pos_dec

• Type: Real

• Availability: with efield_flag = True.

• Description: Zone in the unit cell where the saw-like potential decreases, 0 < efield_pos_dec < 1.

• Default: 0.1

efield_amp

• Type: Real

• Availability: with efield_flag = True.

• Description: Amplitude of the electric field. The saw-like potential increases with slope efield_amp in the region from efield_pos_max+efield_pos_dec-1) to (efield_pos_max), then decreases until (efield_pos_max+efield_pos_dec), in units of the crystal vector efield_dir.

Note: The change of slope of this potential must be located in the empty region, or else unphysical forces will result.

• Default: 0.0

• Unit: a.u., 1 a.u. = 51.4220632*10^10 V/m.

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Gate field (compensating charge)

These variables are relevant to gate field (compensating charge) Detailed introduction

gate_flag

• Type: Boolean

• Description: Controls the addition of compensating charge by a charged plate for charged cells.

  • true: A charged plate is placed at the zgate position to add compensating charge. The direction is determined by efield_dir.

  • false: No compensating charge is added.

• Default: false

zgate

• Type: Real

• Description: position of the charged plate in the unit cell

• Unit: Unit cell size

• Default: 0.5

• Constraints: 0 <= zgate < 1

block

• Type: Boolean

• Description: Controls the addition of a potential barrier to prevent electron spillover.

  • true: A potential barrier is added from block_down to block_up with a height of block_height. If dip_cor_flag is set to true, efield_pos_dec is used to smoothly increase and decrease the potential barrier.

  • false: No potential barrier is added.

• Default: false

block_down

• Type: Real

• Description: lower beginning of the potential barrier

• Unit: Unit cell size

• Default: 0.45

• Constraints: 0 <= block_down < block_up < 1

block_up

• Type: Real

• Description: upper beginning of the potential barrier

• Unit: Unit cell size

• Default: 0.55

• Constraints: 0 <= block_down < block_up < 1

block_height

• Type: Real

• Description: height of the potential barrier

• Unit: Rydberg

• Default: 0.1

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Exact Exchange

These variables are relevant when using hybrid functionals.

Availablity: dft_functional==hse/hf/pbe0/scan0/opt_orb or rpa==True, and basis_type==lcao/lcao_in_pw

exx_hybrid_alpha

• Type: Real

• Description: fraction of Fock exchange in hybrid functionals, so that \(E_{X}=\alpha E_{X}+(1-\alpha)E_{X,\text{LDA/GGA}}\)

• Default:

  • 1: if dft_functional==hf

  • 0.25: else

exx_hse_omega

• Type: Real

• Description: range-separation parameter in HSE functional, such that \(1/r=\text{erfc}(\omega r)/r+\text{erf}(\omega r)/r\)

• Default: 0.11

exx_separate_loop

• Type: Boolean

• Description: There are two types of iterative approaches provided by ABACUS to evaluate Fock exchange.

  • False: Start with a GGA-Loop, and then Hybrid-Loop, in which EXX Hamiltonian \(H_{exx}\) is updated with electronic iterations.

  • True: A two-step method is employed, i.e. in the inner iterations, density matrix is updated, while in the outer iterations, \(H_{exx}\) is calculated based on density matrix that converges in the inner iteration.

• Default: True

exx_hybrid_step

• Type: Integer

• Availability: exx_seperate_loop==1

• Description: the maximal iteration number of the outer-loop, where the Fock exchange is calculated

• Default: 100

exx_mixing_beta

• Type: Real

• Availability: exx_seperate_loop==1

• Description: mixing_beta for densty matrix in each iteration of the outer-loop

• Default: 1.0

exx_lambda

• Type: Real

• Availability: basis_type==lcao_in_pw

• Description: It is used to compensate for divergence points at G=0 in the evaluation of Fock exchange using lcao_in_pw method.

• Default: 0.3

exx_pca_threshold

• Type: Real

• Description: To accelerate the evaluation of four-center integrals (\(ik|jl\)), the product of atomic orbitals are expanded in the basis of auxiliary basis functions (ABF): \(\Phi_{i}\Phi_{j}\sim C^{k}_{ij}P_{k}\). The size of the ABF (i.e. number of \(P_{k}\)) is reduced using principal component analysis. When a large PCA threshold is used, the number of ABF will be reduced, hence the calculation becomes faster. However, this comes at the cost of computational accuracy. A relatively safe choice of the value is 1e-4.

• Default: 1E-4

exx_c_threshold

• Type: Real

• Description: See also the entry exx_pca_threshold. Smaller components (less than exx_c_threshold) of the \(C^{k}_{ij}\) matrix are neglected to accelerate calculation. The larger the threshold is, the faster the calculation and the lower the accuracy. A relatively safe choice of the value is 1e-4.

• Default: 1E-4

exx_v_threshold

• Type: Real

• Description: See also the entry exx_pca_threshold. With the approximation \(\Phi_{i}\Phi_{j}\sim C^{k}_{ij}P_{k}\), the four-center integral in Fock exchange is expressed as \((ik|jl)=\Sigma_{a,b}C^{a}_{ij}V_{ab}C^{b}_{kl}\), where \(V_{ab}=(P_{a}|P_{b})\) is a double-center integral. Smaller values of the V matrix can be truncated to accelerate calculation. The larger the threshold is, the faster the calculation and the lower the accuracy. A relatively safe choice of the value is 0, i.e. no truncation.

• Default: 1E-1

exx_dm_threshold

• Type: Real

• Description: The Fock exchange can be expressed as \(\Sigma_{k,l}(ik|jl)D_{kl}\) where D is the density matrix. Smaller values of the density matrix can be truncated to accelerate calculation. The larger the threshold is, the faster the calculation and the lower the accuracy. A relatively safe choice of the value is 1e-4.

• Default: 1E-4

exx_c_grad_threshold

• Type: Real

• Description: See also the entry exx_pca_threshold. \(\nabla C^{k}_{ij}\) is used in force and stress. Smaller components (less than exx_c_grad_threshold) of the \(\nabla C^{k}_{ij}\) matrix are neglected to accelerate calculation. The larger the threshold is, the faster the calculation and the lower the accuracy. A relatively safe choice of the value is 1e-4.

• Default: 1E-4

exx_v_grad_threshold

• Type: Real

• Description: See also the entry exx_pca_threshold. With the approximation \(\Phi_{i}\Phi_{j}\sim C^{k}_{ij}P_{k}\), the four-center integral in Fock exchange is expressed as \((ik|jl)=\Sigma_{a,b}C^{a}_{ij}V_{ab}C^{b}_{kl}\), where \(V_{ab}=(P_{a}|P_{b})\) is a double-center integral. \(\nabla V_{ab}\) is used in force and stress. Smaller values of the V matrix can be truncated to accelerate calculation. The larger the threshold is, the faster the calculation and the lower the accuracy. A relatively safe choice of the value is 0, i.e. no truncation.

• Default: 1E-1

exx_schwarz_threshold

• Type: Real

• Description: In practice the four-center integrals are sparse, and using Cauchy-Schwartz inequality, we can find an upper bound of each integral before carrying out explicit evaluations. Those that are smaller than exx_schwarz_threshold will be truncated. The larger the threshold is, the faster the calculation and the lower the accuracy. A relatively safe choice of the value is 1e-5. (Currently not used)

• Default: 0

exx_cauchy_threshold

• Type: Real

• Description: In practice the Fock exchange matrix is sparse, and using Cauchy-Schwartz inequality, we can find an upper bound of each matrix element before carrying out explicit evaluations. Those that are smaller than exx_cauchy_threshold will be truncated. The larger the threshold is, the faster the calculation and the lower the accuracy. A relatively safe choice of the value is 1e-7.

• Default: 1E-7

exx_cauchy_force_threshold

• Type: Real

• Description: In practice the Fock exchange matrix in force is sparse, and using Cauchy-Schwartz inequality, we can find an upper bound of each matrix element before carrying out explicit evaluations. Those that are smaller than exx_cauchy_force_threshold will be truncated. The larger the threshold is, the faster the calculation and the lower the accuracy. A relatively safe choice of the value is 1e-7.

• Default: 1E-7

exx_cauchy_stress_threshold

• Type: Real

• Description: In practice the Fock exchange matrix in stress is sparse, and using Cauchy-Schwartz inequality, we can find an upper bound of each matrix element before carrying out explicit evaluations. Those that are smaller than exx_cauchy_stress_threshold will be truncated. The larger the threshold is, the faster the calculation and the lower the accuracy. A relatively safe choice of the value is 1e-7.

• Default: 1E-7

exx_ccp_threshold

• Type: Real

• Description: It is related to the cutoff of on-site Coulomb potentials. (Currently not used)

• Default: 1e-8

exx_ccp_rmesh_times

• Type: Real

• Description: This parameter determines how many times larger the radial mesh required for calculating Columb potential is to that of atomic orbitals. For HSE, setting it to 1 is enough. But for PBE0, a much larger number must be used.

• Default:

  • 1.5: if dft_functional==hse

  • 5: else

exx_distribute_type

• Type: String

• Description: When running in parallel, the evaluation of Fock exchange is done by distributing atom pairs on different processes, then gather the results. exx_distribute_type governs the mechanism of distribution. Available options are htime, order, kmean1 and kmeans2.

  • order: Atom pairs are simply distributed by their orders.

  • htime: The balance in time is achieved on each processor, hence if the memory is sufficient, this is the recommended method.

  • kmeans1 , kmeans2: Two methods where the k-means clustering method is used to reduce memory requirement. They might be necessary for very large systems. (Currently not used)

• Default: htime

exx_opt_orb_lmax

• Type: Integer

• Availability: dft_functional==opt_orb

• Description: The maximum l of the spherical Bessel functions, when the radial part of opt-ABFs are generated as linear combinations of spherical Bessel functions. A reasonable choice is 2.

• Default: 0

exx_opt_orb_ecut

• Type: Real

• Availability: dft_functional==opt_orb

• Description: The cut-off of plane wave expansion, when the plane wave basis is used to optimize the radial ABFs. A reasonable choice is 60.

• Default: 0

• Unit: Ry

exx_opt_orb_tolerence

• Type: Real

• Availability: dft_functional==opt_orb

• Description: The threshold when solving for the zeros of spherical Bessel functions. A reasonable choice is 1e-12.

• Default: 0

exx_real_number

• Type: Boolean

• Description:

  • True: Enforce LibRI to use double data type.

  • False: Enforce LibRI to use complex data type.

• Default: depends on the gamma_only option

  • True: if gamma_only

  • False: else

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Molecular dynamics

These variables are used to control molecular dynamics calculations. For more information, please refer to md.md in detail.

md_type

• Type: String

• Description: Control the algorithm to integrate the equation of motion for molecular dynamics (MD), see md.md in detail.

  • fire: a MD-based relaxation algorithm, named fast inertial relaxation engine.

  • nve: NVE ensemble with velocity Verlet algorithm.

  • nvt: NVT ensemble, see md_thermostat in detail.

  • npt: Nose-Hoover style NPT ensemble, see md_pmode in detail.

  • langevin: NVT ensemble with Langevin thermostat, see md_damp in detail.

  • msst: MSST method, see msst_direction, msst_vel, msst_qmass, msst_vis, msst_tscale in detail.

• Default: nvt

md_nstep

• Type: Integer

• Description: The total number of molecular dynamics steps.

• Default: 10

md_dt

• Type: Real

• Description: The time step used in molecular dynamics calculations.

• Default: 1.0

• Unit: fs

md_thermostat

• Type: String

• Description: Specify the temperature control method used in NVT ensemble.

  • nhc: Nose-Hoover chain, see md_tfreq and md_tchain in detail.

  • anderson: Anderson thermostat, see md_nraise in detail.

  • berendsen: Berendsen thermostat, see md_nraise in detail.

  • rescaling: velocity Rescaling method 1, see md_tolerance in detail.

  • rescale_v: velocity Rescaling method 2, see md_nraise in detail.

• Default: nhc

md_tfirst, md_tlast

• Type: Real

• Description: The temperature used in molecular dynamics calculations.

  If md_tfirst is unset or less than zero, init_vel is autoset to be true. If init_vel is true, the initial temperature will be determined by the velocities read from STRU. In this case, if velocities are unspecified in STRU, the initial temperature is set to zero.

  If md_tfirst is set to a positive value and init_vel is true simultaneously, please make sure they are consistent, otherwise abacus will exit immediately.

  Note that md_tlast is only used in NVT/NPT simulations. If md_tlast is unset or less than zero, md_tlast is set to md_tfirst. If md_tlast is set to be different from md_tfirst, ABACUS will automatically change the temperature from md_tfirst to md_tlast.

• Default: No default

• Unit: K

md_restart

• Type: Boolean

• Description: Control whether to restart molecular dynamics calculations and time-dependent density functional theory calculations.

  • True: ABACUS will read in ${read_file_dir}/Restart_md.dat to determine the current step ${md_step}, then read in the corresponding STRU_MD_${md_step} in the folder OUT.$suffix/STRU/ automatically. For tddft, ABACUS will also read in LOWF_K_${kpoint} of the last step (You need to set out_wfc_lcao=1 and out_app_flag=0 to obtain this file).

  • False: ABACUS will start molecular dynamics calculations normally from the first step.

• Default: False

md_restartfreq

• Type: Integer

• Description: The output frequency of OUT.${suffix}/Restart_md.dat and structural files in the directory OUT.${suffix}/STRIU/, which are used to restart molecular dynamics calculations, see md_restart in detail.

• Default: 5

md_dumpfreq

• Type: Integer

• Description: The output frequency of OUT.${suffix}/MD_dump in molecular dynamics calculations, which including the information of lattices and atoms.

• Default: 1

dump_force

• Type: Boolean

• Description: Whether to output atomic forces into the file OUT.${suffix}/MD_dump.

• Default: True

dump_vel

• Type: Boolean

• Description: Whether to output atomic velocities into the file OUT.${suffix}/MD_dump.

• Default: True

dump_virial

• Type: Boolean

• Description: Whether to output lattice virials into the file OUT.${suffix}/MD_dump.

• Default: True

md_seed

• Type: Integer

• Description: The random seed to initialize random numbers used in molecular dynamics calculations.

  • < 0: No srand() function is called.

  • >= 0: The function srand(md_seed) is called.

• Default: -1

md_tfreq

• Type: Real

• Description: Control the frequency of temperature oscillations during the simulation. If it is too large, the temperature will fluctuate violently; if it is too small, the temperature will take a very long time to equilibrate with the atomic system.

  Note: It is a system-dependent empirical parameter, ranging from 1/(40*md_dt) to 1/(100*md_dt). An improper choice might lead to the failure of jobs.

• Default: 1/40/md_dt

• Unit: \(\mathrm{fs^{-1}}\)

md_tchain

• Type: Integer

• Description: Number of thermostats coupled with the particles in the NVT/NPT ensemble based on the Nose-Hoover style non-Hamiltonian equations of motion.

• Default: 1

md_pmode

• Type: String

• Description: Specify the cell fluctuation mode in NPT ensemble based on the Nose-Hoover style non-Hamiltonian equations of motion.

  • iso: The three diagonal elements of the lattice are fluctuated isotropically.

  • aniso: The three diagonal elements of the lattice are fluctuated anisotropically.

  • tri: The lattice must be a lower-triangular matrix, and all six freedoms are fluctuated.

• Default: iso

• Relavent: md_tfreq, md_tchain, md_pcouple, md_pfreq, and md_pchain.

md_prec_level

• Type: Integer

• Description: Determine the precision level of variable-cell molecular dynamics calculations.

  • 0: FFT grids do not change, only G vectors and K vectors are changed due to the change of lattice vector. This level is suitable for cases where the variation of the volume and shape is not large, and the efficiency is relatively higher.

  • 2: FFT grids change per step. This level is suitable for cases where the variation of the volume and shape is large, such as the MSST method. However, accuracy comes at the cost of efficiency.

• Default: 0

ref_cell_factor

• Type: Real

• Description: Construct a reference cell bigger than the initial cell. The reference cell has to be large enough so that the lattice vectors of the fluctuating cell do not exceed the reference lattice vectors during MD. Typically, 1.02 ~ 1.10 is sufficient. However, the cell fluctuations depend on the specific system and thermodynamic conditions. So users must test for a proper choice. This parameters should be used in conjunction with erf_ecut, erf_height, and erf_sigma.

• Default: 1.0

md_pcouple

• Type: String

• Description: The coupled lattice vectors will scale proportionally in NPT ensemble based on the Nose-Hoover style non-Hamiltonian equations of motion.

  • none: Three lattice vectors scale independently.

  • xyz: Lattice vectors x, y, and z scale proportionally.

  • xy: Lattice vectors x and y scale proportionally.

  • xz: Lattice vectors x and z scale proportionally.

  • yz: Lattice vectors y and z scale proportionally.

• Default: none

md_pfirst, md_plast

• Type: Real

• Description: The target pressure used in NPT ensemble simulations, the default value of md_plast is md_pfirst. If md_plast is set to be different from md_pfirst, ABACUS will automatically change the target pressure from md_pfirst to md_plast.

• Default: No default

• Unit: kbar

md_pfreq

• Type: Real

• Description: The frequency of pressure oscillations during the NPT ensemble simulation. If it is too large, the pressure will fluctuate violently; if it is too small, the pressure will take a very long time to equilibrate with the atomic system.

  Note: It is a system-dependent empirical parameter. An improper choice might lead to the failure of jobs.

• Default: 1/400/md_dt

• Unit: \(\mathrm{kbar^{-1}}\)

md_pchain

• Type: Integer

• Description: The number of thermostats coupled with the barostat in the NPT ensemble based on the Nose-Hoover style non-Hamiltonian equations of motion.

• Default: 1

lj_rcut

• Type: Real

• Description: Cut-off radius for Leonard Jones potential.

• Default: 8.5 (for He)

• Unit: Angstrom

lj_epsilon

• Type: Real

• Description: The value of epsilon for Leonard Jones potential.

• Default: 0.01032 (for He)

• Unit: eV

lj_sigma

• Type: Real

• Description: The value of sigma for Leonard Jones potential.

• Default: 3.405 (for He)

• Unit: Angstrom

pot_file

• Type: String

• Description: The filename of DP potential files, see md.md in detail.

• Default: graph.pb

msst_direction

• Type: Integer

• Description: The direction of the shock wave in the MSST method.

  • 0: x direction

  • 1: y direction

  • 2: z direction

• Default: 2

msst_vel

• Type: Real

• Description: The velocity of the shock wave in the MSST method.

• Default: 0.0

• Unit: Angstrom/fs

msst_vis

• Type: Real

• Description: Artificial viscosity in the MSST method.

• Default: 0.0

• Unit: g/(mol*Angstrom*fs)

msst_tscale

• Type: Real

• Description: The reduction percentage of the initial temperature used to compress volume in the MSST method.

• Default: 0.01

msst_qmass

• Type: Real

• Description: Inertia of the extended system variable. You should set a number larger than 0.

• Default: No default

• Unit: \(\mathrm{g^{2}/(mol^{2}*Angstrom^{4})}\)

md_damp

• Type: Real

• Description: The damping parameter used to add fictitious force in the Langevin method.

• Default: 1.0

• Unit: fs

md_tolerance

• Type: Real

• Description: Thr temperature tolerance for velocity rescaling. Velocities are rescaled if the current and target temperature differ more than md_tolerance.

• Default: 100.0

• Unit: K

md_nraise

• Type: Integer

• Description:

  • Anderson: The “collision frequency” parameter is given as 1/md_nraise.

  • Berendsen: The “rise time” parameter is given in units of the time step: tau = md_nraise*md_dt, so md_dt/tau = 1/md_nraise.

  • Rescale_v: Every md_nraise steps the current temperature is rescaled to the target temperature.

• Default: 1

cal_syns

• Type: Boolean

• Description: Whether the asynchronous overlap matrix is calculated for Hefei-NAMD.

• Default: False

dmax

• Type: Real

• Description: The maximum displacement of all atoms in one step. This parameter is useful when cal_syns = True.

• Default: 0.01

• Unit: bohr

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DFT+U correction

These variables are used to control DFT+U correlated parameters

dft_plus_u

• Type: Boolean

• Description: Determines whether to calculate the plus U correction, which is especially important for correlated electrons.

  • True: Calculate plus U correction.

  • False: Do not calculate plus U correction.

• Default: False

orbital_corr

• Type: Integer

• Description: Specifies which orbits need plus U correction for each atom type (\(l_1,l_2,l_3,\ldots\) for atom type 1, 2, 3, respectively).

  • -1: The plus U correction will not be calculated for this atom.

  • 1: For p-electron orbits, the plus U correction is needed.

  • 2: For d-electron orbits, the plus U correction is needed.

  • 3: For f-electron orbits, the plus U correction is needed.

• Default: None

hubbard_u

• Type: Real

• Description: Specifies the Hubbard Coulomb interaction parameter U (eV) in plus U correction, which should be specified for each atom unless the Yukawa potential is used.

Note: Since only the simplified scheme by Duradev is implemented, the ‘U’ here is actually U-effective, which is given by Hubbard U minus Hund J.

• Default: 0.0

yukawa_potential

• Type: Boolean

• Description: Determines whether to use the local screen Coulomb potential method to calculate the values of U and J.

  • True: hubbard_u does not need to be specified.

  • False: hubbard_u does need to be specified.

• Default: False

yukawa_lambda

• Type: Real

• Availability: DFT+U with yukawa_potential = True.

• Description: The screen length of Yukawa potential. If left to default, the screen length will be calculated as an average of the entire system. It’s better to stick to the default setting unless there is a very good reason.

• Default: Calculated on the fly.

omc

• Type: Integer

• Description: The parameter controls the form of occupation matrix control used.

  • 0: No occupation matrix control is performed, and the onsite density matrix will be calculated from wavefunctions in each SCF step.

  • 1: The first SCF step will use an initial density matrix read from a file named [initial_onsite.dm](http://initial_onsite.dm/), but for later steps, the onsite density matrix will be updated.

  • 2: The same onsite density matrix from initial_onsite.dm will be used throughout the entire calculation.

Note : The easiest way to create initial_onsite.dm is to run a DFT+U calculation, look for a file named onsite.dm in the OUT.prefix directory, and make replacements there. The format of the file is rather straight-forward.

• Default: 0

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vdW correction

These variables are used to control vdW-corrected related parameters.

vdw_method

• Type: String

• Description: Specifies the method used for Van der Waals (VdW) correction. Available options are:

  • d2: Grimme’s D2 dispersion correction method

  • d3_0: Grimme’s DFT-D3(0) dispersion correction method

  • d3_bj: Grimme’s DFTD3(BJ) dispersion correction method

  • none: no vdW correction

• Default: none

vdw_s6

• Type: Real

• Availability: vdw_method is set to d2, d3_0, or d3_bj

• Description: This scale factor is used to optimize the interaction energy deviations in van der Waals (vdW) corrected calculations. The recommended values of this parameter are dependent on the chosen vdW correction method and the DFT functional being used. For DFT-D2, the recommended values are 0.75 (PBE), 1.2 (BLYP), 1.05 (B-P86), 1.0 (TPSS), and 1.05 (B3LYP). For DFT-D3, recommended values with different DFT functionals can be found on the here. The default value of this parameter in ABACUS is set to be the recommended value for PBE.

• Default:

  • 0.75: if vdw_method is set to d2

  • 1.0: if vdw_method is set to d3_0 or d3_bj

vdw_s8

• Type: Real

• Availability: vdw_method is set to d3_0 or d3_bj

• Description: This scale factor is relevant for D3(0) and D3(BJ) van der Waals (vdW) correction methods. The recommended values of this parameter with different DFT functionals can be found on the webpage. The default value of this parameter in ABACUS is set to be the recommended value for PBE.

• Default:

  • 0.722: if vdw_method is set to d3_0

  • 0.7875: if vdw_method is set to d3_bj

vdw_a1

• Type: Real

• Availability: vdw_method is set to d3_0 or d3_bj

• Description: This damping function parameter is relevant for D3(0) and D3(BJ) van der Waals (vdW) correction methods. The recommended values of this parameter with different DFT functionals can be found on the webpage. The default value of this parameter in ABACUS is set to be the recommended value for PBE.

• Default:

  • 1.217: if vdw_method is set to d3_0

  • 0.4289: if vdw_method is set to d3_bj

vdw_a2

• Type: Real

• Availability: vdw_method is set to d3_0 or d3_bj

• Description: This damping function parameter is only relevant for D3(0) and D3(BJ) van der Waals (vdW) correction methods. The recommended values of this parameter with different DFT functionals can be found on the webpage. The default value of this parameter in ABACUS is set to be the recommended value for PBE.

• Default:

  • 1.0: if vdw_method is set to d3_0

  • 4.4407: if vdw_method is set to d3_bj

vdw_d

• Type: Real

• Availability: vdw_method is set to d2

• Description: Controls the damping rate of the damping function in the DFT-D2 method.

• Default: 20

vdw_abc

• Type: Integer

• Availability: vdw_method is set to d3_0 or d3_bj

• Description: Determines whether three-body terms are calculated for DFT-D3 methods.

  • True: ABACUS will calculate the three-body term.

  • False: The three-body term is not included.

• Default: False

vdw_C6_file

• Type: String

• Availability: vdw_method is set to d2

• Description: Specifies the name of the file containing \(C_6\) parameters for each element when using the D2 method. If not set, ABACUS uses the default \(C_6\) parameters (Jnm6/mol) stored in the program. To manually set the \(C_6\) parameters, provide a file containing the parameters. An example is given by:

  H  0.1
  Si 9.0
  

  Namely, each line contains the element name and the corresponding \(C_6\) parameter.

• Default: default

vdw_C6_unit

• Type: String

• Availability: vdw_C6_file is not default

• Description: Specifies the unit of the provided \(C_6\) parameters in the D2 method. Available options are:

  • Jnm6/mol (J·nm^6/mol)

  • eVA (eV·Angstrom)

• Default: Jnm6/mol

vdw_R0_file

• Type: String

• Availability: vdw_method is set to d2

• Description: Specifies the name of the file containing \(R_0\) parameters for each element when using the D2 method. If not set, ABACUS uses the default \(R_0\) parameters (Angstrom) stored in the program. To manually set the \(R_0\) parameters, provide a file containing the parameters. An example is given by:

  Li 1.0
  Cl 2.0
  

  Namely, each line contains the element name and the corresponding \(R_0\) parameter.

• Default: default

vdw_R0_unit

• Type: String

• Availability: vdw_R0_file is not default

• Description: Specifies the unit for the \(R_0\) parameters in the D2 method when manually set by the user. Available options are:

  • A (Angstrom)

  • Bohr

• Default: A

vdw_cutoff_type

• Type: String

• Description: Determines the method used for specifying the cutoff radius in periodic systems when applying Van der Waals correction. Available options are:

  • radius: The supercell is selected within a sphere centered at the origin with a radius defined by vdw_cutoff_radius.

  • period: The extent of the supercell is explicitly specified using the vdw_cutoff_period keyword.

• Default: radius

vdw_cutoff_radius

• Type: Real

• Availability: vdw_cutoff_type is set to radius

• Description: Defines the radius of the cutoff sphere when vdw_cutoff_type is set to radius. The default values depend on the chosen vdw_method.

• Default:

  • 56.6918 if vdw_method is set to d2

  • 95 if vdw_method is set to d3_0 or d3_bj

• Unit: defined by vdw_radius_unit (default Bohr)

vdw_radius_unit

• Type: String

• Availability: vdw_cutoff_type is set to radius

• Description: specify the unit of vdw_cutoff_radius. Available options are:

  • A(Angstrom)

  • Bohr

• Default: Bohr

vdw_cutoff_period

• Type: Integer Integer Integer

• Availability: vdw_cutoff_type is set to period

• Description: The three integers supplied here explicitly specify the extent of the supercell in the directions of the three basis lattice vectors.

• Default: 3 3 3

vdw_cn_thr

• Type: Real

• Availability: vdw_method is set to d3_0 or d3_bj

• Description: The cutoff radius when calculating coordination numbers.

• Default: 40

• Unit: defined by vdw_cn_thr_unit (default: Bohr)

vdw_cn_thr_unit

• Type: String

• Description: Unit of the coordination number cutoff (vdw_cn_thr). Available options are:

  • A(Angstrom)

  • Bohr

• Default: Bohr

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Berry phase and wannier90 interface

These variables are used to control berry phase and wannier90 interface parameters. Detail introduce

berry_phase

• Type: Boolean

• Description: controls the calculation of Berry phase

  • true: Calculate Berry phase.

  • false: Do not calculate Berry phase.

• Default: false

gdir

• Type: Integer

• Description: the direction of the polarization in the lattice vector for Berry phase calculation

  • 1: Calculate the polarization in the direction of the lattice vector a_1 defined in the STRU file.

  • 2: Calculate the polarization in the direction of the lattice vector a_2 defined in the STRU file.

  • 3: Calculate the polarization in the direction of the lattice vector a_3 defined in the STRU file.

• Default: 3

towannier90

• Type: Integer

• Description: Controls the generation of files for the Wannier90 code.

  • 1: Generate files for the Wannier90 code.

  • 0: Do not generate files for the Wannier90 code.

• Default: 0

nnkpfile

• Type: String

• Description: the file name generated when running “wannier90 -pp …” command

• Default: seedname.nnkp

wannier_spin

• Type: String

• Description: the spin direction for the Wannier function calculation when nspin is set to 2

  • “up”: Calculate spin up for the Wannier function.

  • “down”: Calculate spin down for the Wannier function.

• Default: “up”

out_wannier_mmn

• Type: Bool

• Description: write the “*.mmn” file or not.

  • 0: don’t write the “*.mmn” file.

  • 1: write the “*.mmn” file.

• Default: 1

out_wannier_amn

• Type: Bool

• Description: write the “*.amn” file or not.

  • 0: don’t write the “*.amn” file.

  • 1: write the “*.amn” file.

• Default: 1

out_wannier_eig

• Type: Bool

• Description: write the “*.eig” file or not.

  • 0: don’t write the “*.eig” file.

  • 1: write the “*.eig” file.

• Default: 1

out_wannier_unk

• Type: Bool

• Description: write the “UNK.*” file or not.

  • 0: don’t write the “UNK.*” file.

  • 1: write the “UNK.*” file.

• Default: 1

out_wannier_wvfn_formatted

• Type: Bool

• Description: write the “UNK.*” file in ASCII format or binary format.

  • 0: write the “UNK.*” file in binary format.

  • 1: write the “UNK.*” file in ASCII format (text file format).

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TDDFT: time dependent density functional theory

td_edm

• Type: Integer

• Description: the method to calculate the energy density matrix

  • 0: new method (use the original formula).

  • 1: old method (use the formula for ground state).

• Default: 0

td_print_eij

• Type: Real

• Description:

  • <0: don’t print \(E_{ij}\).

  • >=0: print the \(E_{ij}\ (<\psi_i|H|\psi_j>\)) elements which are larger than td_print_eij.

• Default: -1

td_propagator

• Type: Integer

• Description: method of propagator

  • 0: Crank-Nicolson.

  • 1: 4th Taylor expansions of exponential.

  • 2: enforced time-reversal symmetry (ETRS).

• Default: 0

td_vext

• Type: Boolean

• Description:

  • True: add a laser material interaction (extern laser field).

  • False: no extern laser field.

• Default: False

td_vext_dire

• Type: String

• Description: If td_vext is True, the td_vext_dire is a string to set the number of electric fields, like td_vext_dire 1 2 representing external electric field is added to the x and y axis at the same time. Parameters of electric field can also be written as a string, like td_gauss_phase 0 1.5707963267948966 representing the Gauss field in the x and y directions has a phase delay of Pi/2. See below for more parameters of electric field.

  • 1: the direction of external light field is along x axis.

  • 2: the direction of external light field is along y axis.

  • 3: the direction of external light field is along z axis.

• Default: 1

td_stype

• Type: Integer

• Description: type of electric field in space domain

  • 0: length gauge.

  • 1: velocity gauge.

• Default: 0

td_ttype

• Type: Integer

• Description: type of electric field in time domain

  • 0: Gaussian type function.

  • 1: Trapezoid function.

  • 2: Trigonometric function.

  • 3: Heaviside function.

  • 4: HHG function.

• Default: 0

td_tstart

• Type: Integer

• Description: number of steps where electric field starts

• Default: 1

td_tend

• Type: Integer

• Description: number of steps where electric field ends

• Default: 100

td_lcut1

• Type: Real

• Description: cut1 of interval in length gauge
  E = E0 , cut1<x<cut2
  E = -E0/(cut1+1-cut2) , x<cut1 or cut2<x<1

• Default: 0.05

td_lcut2

• Type: Real

• Description: cut2 of interval in length gauge
  E = E0 , cut1<x<cut2
  E = -E0/(cut1+1-cut2) , x<cut1 or cut2<x<1

• Default: 0.05

td_gauss_freq

• Type: Real

• Description: frequency (freq) of Gauss type electric field (fs^-1)
  amp*cos(2pi*freq(t-t0)+phase)exp(-(t-t0)^2/2sigma^2)

• Default: 22.13

td_gauss_phase

• Type: Real

• Description: phase of Gauss type electric field
  amp*(2pi*freq(t-t0)+phase)exp(-(t-t0)^2/2sigma^2)

• Default: 0.0

td_gauss_sigma

• Type: Real

• Description: sigma of Gauss type electric field (fs)
  amp*cos(2pi*freq(t-t0)+phase)exp(-(t-t0)^2/2sigma^2)

• Default: 30.0

td_gauss_t0

• Type: Real

• Description: step number of time center (t0) of Gauss type electric field
  amp*cos(2pi*freq(t-t0)+phase)exp(-(t-t0)^2/2sigma^2)

• Default: 100

td_gauss_amp

• Type: Real

• Description: amplitude (amp) of Gauss type electric field (V/Angstrom)
  amp*cos(2pi*freq(t-t0)+phase)exp(-(t-t0)^2/2sigma^2)

• Default: 0.25

td_trape_freq

• Type: Real

• Description: frequency (freq) of Trapezoid type electric field (fs^-1)
  E = amp*cos(2pi*freq*t+phase) t/t1 , t<t1
  E = amp*cos(2pi*freq*t+phase) , t1<t<t2
  E = amp*cos(2pi*freq*t+phase) (1-(t-t2)/(t3-t2)) , t2<t<t3
  E = 0 , t>t3

• Default: 1.60

td_trape_phase

• Type: Real

• Description: phase of Trapezoid type electric field
  E = amp*cos(2pi*freq*t+phase) t/t1 , t<t1
  E = amp*cos(2pi*freq*t+phase) , t1<t<t2
  E = amp*cos(2pi*freq*t+phase) (1-(t-t2)/(t3-t2)) , t2<t<t3
  E = 0 , t>t3

• Default: 0.0

td_trape_t1

• Type: Real

• Description: step number of time interval 1 (t1) of Trapezoid type electric field
  E = amp*cos(2pi*freq*t+phase) t/t1 , t<t1
  E = amp*cos(2pi*freq*t+phase) , t1<t<t2
  E = amp*cos(2pi*freq*t+phase) (1-(t-t2)/(t3-t2)) , t2<t<t3
  E = 0 , t>t3

• Default: 1875

td_trape_t2

• Type: Real

• Description: step number of time interval 2 (t2) of Trapezoid type electric field
  E = amp*cos(2pi*freq*t+phase) t/t1 , t<t1
  E = amp*cos(2pi*freq*t+phase) , t1<t<t2
  E = amp*cos(2pi*freq*t+phase) (1-(t-t2)/(t3-t2)) , t2<t<t3
  E = 0 , t>t3

• Default: 5625

td_trape_t3

• Type: Real

• Description: step number of time interval 3 (t3) of Trapezoid type electric field
  E = amp*cos(2pi*freq*t+phase) t/t1 , t<t1
  E = amp*cos(2pi*freq*t+phase) , t1<t<t2
  E = amp*cos(2pi*freq*t+phase) (1-(t-t2)/(t3-t2)) , t2<t<t3
  E = 0 , t>t3

• Default: 7500

td_trape_amp

• Type: Real

• Description: amplitude (amp) of Trapezoid type electric field (V/Angstrom)
  E = amp*cos(2pi*freq*t+phase) t/t1 , t<t1
  E = amp*cos(2pi*freq*t+phase) , t1<t<t2
  E = amp*cos(2pi*freq*t+phase) (1-(t-t2)/(t3-t2)) , t2<t<t3
  E = 0 , t>t3

• Default: 2.74

td_trigo_freq1

• Type: Real

• Description: frequency 1 (freq1) of Trigonometric type electric field (fs^-1)
  amp*cos(2*pi*freq1*t+phase1)*sin(2*pi*freq2*t+phase2)^2

• Default: 1.164656

td_trigo_freq2

• Type: Real

• Description: frequency 2 (freq2) of Trigonometric type electric field (fs^-1)
  amp*cos(2*pi*freq1*t+phase1)*sin(2*pi*freq2*t+phase2)^2

• Default: 0.029116

td_trigo_phase1

• Type:Real

• Description: phase 1 (phase1) of Trigonometric type electric field
  amp*cos(2*pi*freq1*t+phase1)*sin(2*pi*freq2*t+phase2)^2

• Default: 0.0

td_trigo_phase2

• Type: Real

• Description: phase 2 (phase2) of Trigonometric type electric field
  amp*cos(2*pi*freq1*t+phase1)*sin(2*pi*freq2*t+phase2)^2

• Default: 0.0

td_trigo_amp

• Type: Real

• Description: amplitude (amp) of Trigonometric type electric field (V/Angstrom)
  amp*cos(2*pi*freq1*t+phase1)*sin(2*pi*freq2*t+phase2)^2

• Default: 2.74

td_heavi_t0

• Type: Real

• Description: step number of switch time (t0) of Heaviside type electric field
  E = amp , t<t0
  E = 0.0 , t>t0

• Default: 100

td_heavi_amp

• Type: Real

• Description: amplitude (amp) of Heaviside type electric field (V/Angstrom)
  E = amp , t<t0
  E = 0.0 , t>t0

• Default: 2.74

td_out_dipole

• Type: Boolean

• Description:

  • True: output dipole.

  • False: do not output dipole.

• Default: False

td_out_efield

• Type: Boolean

• Description: The unit of output file is atomic unit (1 a.u. = 1 Ry/(bohr \(\cdot\) e) = 51.422 V/Angstrom).

  • True: output efield.

  • False: do not output efield.

• Default: False

ocp

• Type: Boolean

• Availability:

  • For PW and LCAO codes. if set to 1, occupations of bands will be setting of “ocp_set”.

  • For TDDFT in LCAO codes. if set to 1, occupations will be constrained since second ionic step.

  • For OFDFT, this feature can’t be used.

• Description:

• True: fix the occupations of bands.

• False: do not fix the occupations of bands.

• Default: False

ocp_set

• Type: String

• Description: If ocp is True, the ocp_set is a string to set the number of occupancy, like ‘1 10 * 1 0 1’ representing the 13 band occupancy, 12th band occupancy 0 and the rest 1, the code is parsing this string into an array through a regular expression.

• Default: none

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Variables useful for debugging

t_in_h

• Type: Boolean

• Description: Specify whether to include kinetic term in obtaining the Hamiltonian matrix.

  • 0: No.

  • 1: Yes.

• Default: 1

vl_in_h

• Type: Boolean

• Description: Specify whether to include local pseudopotential term in obtaining the Hamiltonian matrix.

  • 0: No.

  • 1: Yes.

• Default: 1

vnl_in_h

• Type: Boolean

• Description: Specify whether to include non-local pseudopotential term in obtaining the Hamiltonian matrix.

  • 0: No.

  • 1: Yes.

• Default: 1

vh_in_h

• Type: Boolean

• Description: Specify whether to include Hartree potential term in obtaining the Hamiltonian matrix.

  • 0: No.

  • 1: Yes.

• Default: 1

vion_in_h

• Type: Boolean

• Description: Specify whether to include local ionic potential term in obtaining the Hamiltonian matrix.

  • 0: No.

  • 1: Yes.

• Default: 1

test_force

• Type: Boolean

• Description: Specify whether to output the detailed components in forces.

  • 0: No.

  • 1: Yes.

• Default: 0

test_stress

• Type: Boolean

• Description: Specify whether to output the detailed components in stress.

  • 0: No.

  • 1: Yes.

• Default: 0

colour

• Type: Boolean

• Description: Specify whether to set the colorful output in terminal.

  • 0: No.

  • 1: Yes.

• Default: 0

test_skip_ewald

• Type: Boolean

• Description: Specify whether to skip the calculation of the ewald energy.

  • 0: No.

  • 1: Yes.

• Default: 0

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Electronic conductivities

Frequency-dependent electronic conductivities can be calculated with Kubo-Greenwood formula [Phys. Rev. B 83, 235120 (2011)].

Onsager coefficients:

\(L_{mn}(\omega)=(-1)^{m+n}\frac{2\pi e^2\hbar^2}{3m_e^2\omega\Omega}\)

\(\times\sum_{ij\alpha\mathbf{k}}W(\mathbf{k})\left(\frac{\epsilon_{i\mathbf{k}}+\epsilon_{j\mathbf{k}}}{2}-\mu\right)^{m+n-2} \times |\langle\Psi_{i\mathbf{k}}|\nabla_\alpha|\Psi_{j\mathbf{k}}\rangle|^2\)

\(\times[f(\epsilon_{i\mathbf{k}})-f(\epsilon_{j\mathbf{k}})]\delta(\epsilon_{j\mathbf{k}}-\epsilon_{i\mathbf{k}}-\hbar\omega).\)

They can also be computed by \(j\)-\(j\) correlation function.

\(L_{mn}=\frac{2e^{m+n-2}}{3\Omega\hbar\omega}\Im[\tilde{C}_{mn}(\omega)]\)

\(\tilde{C}_{mn}=\int_0^\infty C_{mn}(t)e^{-i\omega t}e^{-\frac{1}{2}(\Delta E)^2t^2}dt\)

\(C_{mn}(t)=-2\theta(t)\Im\left\{Tr\left[\sqrt{\hat f}\hat{j}_m(1-\hat{f})e^{i\frac{\hat{H}}{\hbar}t}\hat{j}_ne^{-i\frac{\hat{H}}{\hbar}t}\sqrt{\hat f}\right]\right\}\),

where \(j_1\) is electric flux and \(j_2\) is thermal flux.

Frequency-dependent electric conductivities: \(\sigma(\omega)=L_{11}(\omega)\).

Frequency-dependent thermal conductivities: \(\kappa(\omega)=\frac{1}{e^2T}\left(L_{22}-\frac{L_{12}^2}{L_{11}}\right)\).

DC electric conductivities: \(\sigma = \lim_{\omega\to 0}\sigma(\omega)\).

Thermal conductivities: \(\kappa = \lim_{\omega\to 0}\kappa(\omega)\).

cal_cond

• Type: Boolean

• Availability: basis_type = pw

• Description: Whether to calculate electronic conductivities.

• Default: False

cond_che_thr

• Type: Real

• Availability: esolver_type = sdft

• Description: Control the error of Chebyshev expansions for conductivities.

• Default: 1e-8

cond_dw

• Type: Real

• Availability: basis_type = pw

• Description: Frequency interval (\(\mathrm{d}\omega\)) for frequency-dependent conductivities.

• Default: 0.1

• Unit: eV

cond_wcut

• Type: Real

• Availability: basis_type = pw

• Description: Cutoff frequency for frequency-dependent conductivities.

• Default: 10.0

• Unit: eV

cond_dt

• Type: Real

• Availability: basis_type = pw

• Description: Time interval (\(\mathrm{d}t\)) to integrate Onsager coefficients.

• Default: 0.02

• Unit: a.u.

cond_dtbatch

• Type: Integer

• Availability: esolver_type = sdft

• Description: exp(iH*dt*cond_dtbatch) is expanded with Chebyshev expansion to calculate conductivities. It is faster but costs more memory.

• Default: 4

cond_fwhm

• Type: Real

• Availability: basis_type = pw

• Description: FWHM for conductivities, \(\mathrm{FWHM}=2*\sqrt{2\ln2}\cdot \Delta E\). Here, we use gaussian functions to approximate \(\delta(E)\approx \frac{1}{\sqrt{2\pi}\Delta E}e^{-\frac{E^2}{2{\Delta E}^2}}\).

• Default: 0.4

• Unit: eV

cond_nonlocal

• Type: Boolean

• Availability: basis_type = pw

• Description: Whether to consider nonlocal potential correction when calculating velocity matrix \(\bra{\psi_i}\hat{v}\ket{\psi_j}\).

  • True: \(m\hat{v}=\hat{p}+\frac{im}{\hbar}[\hat{V}_{NL},\hat{r}]\).

  • False: \(m\hat{v}\approx\hat{p}\).

• Default: True

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Implicit solvation model

These variables are used to control the usage of implicit solvation model. This approach treats the solvent as a continuous medium instead of individual “explicit” solvent molecules, which means that the solute is embedded in an implicit solvent and the average over the solvent degrees of freedom becomes implicit in the properties of the solvent bath.

imp_sol

• Type: Boolean

• Description: calculate implicit solvation correction

• Default: False

eb_k

• Type: Real

• Availability: imp_sol is true.

• Description: the relative permittivity of the bulk solvent, 80 for water

• Default: 80

tau

• Type: Real

• Description: The effective surface tension parameter that describes the cavitation, the dispersion, and the repulsion interaction between the solute and the solvent which are not captured by the electrostatic terms

• Default: 1.0798e-05

• Unit: \(Ry/Bohr^{2}\)

sigma_k

• Type: Real

• Description: the width of the diffuse cavity that is implicitly determined by the electronic structure of the solute

• Default: 0.6

nc_k

• Type: Real

• Description: the value of the electron density at which the dielectric cavity forms

• Default: 0.00037

• Unit: \(Bohr^{-3}\)

Deltaspin

These variables are used to control the usage of deltaspin functionality.

sc_mag_switch

• Type: boolean

• Description: the switch of deltaspin functionality

  • 0: no deltaspin

  • 1: use the deltaspin method to constrain atomic magnetic moments

• Default: 0

decay_grad_switch

• Type: boolean

• Description: the switch of decay gradient method

  • 0: no decay gradient method

  • 1: use the decay gradient method and set ScDecayGrad in the file specified by sc_file. ScDecayGrad is an element dependent parameter, which is used to control the decay rate of the gradient of the magnetic moment.

• Default: 0

sc_thr

• Type: Real

• Description: the threshold of the spin constraint atomic magnetic moment

• Default: 1e-6

• Unit: Bohr Mag (\muB)

nsc

• Type: Integer

• Description: the maximum number of steps in the inner lambda loop

• Default: 100

nsc_min

• Type: Integer

• Description: the minimum number of steps in the inner lambda loop

• Default: 2

alpha_trial

• Type: Real

• Description: initial trial step size for lambda in eV/uB^2

• Default: 0.01

• Unit: eV/uB^2

sccut

• Type: Real

• Description: restriction of step size in eV/uB

• Default: 3

• Unit: eV/uB

sc_file

• Type: String

• Description: the file in json format to specify atomic constraining parameters. An example of the sc_file json file is shown below for the nspin 4 case:

[
    {
        "element": "Fe",
        "itype": 0,
        "ScDecayGrad": 0.9,
        "ScAtomData": [
            {
                "index": 0,
                "lambda": [0, 0, 0],
                "target_mag": [2.0, 0.0, 0.0],
                "constrain": [1,1,1]
            },
            {
                "index": 1,
                "lambda": [0, 0, 0],
                "target_mag_val": 2.0,
                "target_mag_angle1": 80.0,
                "target_mag_angle2": 0.0,
                "constrain": [1,1,1]
            }
        ]
    }
]

and

[
    {
        "element": "Fe",
        "itype": 0,
        "ScDecayGrad": 0.9,
        "ScAtomData": [
            {
                "index": 0,
                "lambda": 0.0,
                "target_mag": 2.0,
                "constrain": 1
            },
            {
                "index": 1,
                "lambda": 0,
                "target_mag": 2.0,
                "constrain": 1
            }
        ]
    }
]

for nspin 2 case. The difference is that lambda, target_mag, and constrain are scalars in nspin 2 case, and are vectors in nspin 4 case.

• Default: none

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