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Problems in band calculation Date: 2023/02/18 17:22 Name: Xinliang Huang   <xilhuang@foxmail.com> Hi, I used OpenMX to calculate the energy band of TaAs, and did not get the results in the literature. I try to use VASP to calculate the energy band, and the results are consistent with those in the literature. I modified some parameters in OpenMX, and did not get the desired results. Problem: The band gap of TaAs calculated by OpenMX appears near Fermi level. Literature: Weng H, Fan C, Fan Z, et al. Weyl semimetallic phase in noncentrometric transition-metal monophophides [J] Physical Review X, 2015, 5(1): 011029. This is my input file: # # File Name # System.CurrrentDirectory        ./    # default=./ System.Name                      taas level.of.stdout                  1    # default=1 (1-3) level.of.fileout                  0    # default=1 (0-2) DATA.PATH                        /job/huangxl_job/software/OpenMX/openmx3.9/DFT_DATA19 # # Definition of Atomic Species # Species.Number      2 <Definition.of.Atomic.Species Ta  Ta7.0-s3p2d2f1  Ta_PBE19 As  As7.0-s3p2d2    As_PBE19 Definition.of.Atomic.Species> # # Atoms # Atoms.Number        4 Atoms.SpeciesAndCoordinates.Unit  FRAC # Ang|AU <Atoms.SpeciesAndCoordinates 1 Ta -0.0008057087488067 -0.0008057087488067 -0.0000000000942729 6.5 6.5 2 Ta   0.7491943122511916  0.2491942662511948  0.4999999849057294 6.5 6.5 3 As   0.4168057437488100  0.4168057087488035  0.0000000000942729 7.5 7.5 4 As   0.1668056887488089  0.6668056837488049  0.4999999850942752 7.5 7.5 Atoms.SpeciesAndCoordinates> Atoms.UnitVectors.Unit            Ang # Ang|AU <Atoms.UnitVectors     6.3691654972648095    0.0040773293499123    0.0000000544190606     4.4827695175525761    4.5244959065801318    0.0000000544196637     -5.4259647933126134  -2.2642854853152357    2.4491228907703277 Atoms.UnitVectors> # # SCF or Electronic System # scf.XcType                GGA-PBE    # LDA|LSDA-CA|LSDA-PW|GGA-PBE scf.SpinPolarization        off        # On|Off|NC scf.SpinOrbit.Coupling      off        # On|Off, default=off scf.ElectronicTemperature  300.0      # default=300 (K) scf.energycutoff          150.0      # default=150 (Ry) scf.maxIter                900        # default=40 scf.EigenvalueSolver      band        # DC|GDC|Cluster|Band scf.Kgrid                10 10 14      # means n1 x n2 x n3 scf.Mixing.Type          rmm-diisk    # Simple|Rmm-Diis|Gr-Pulay|Kerker|Rmm-Diisk scf.Init.Mixing.Weight    0.01        # default=0.30 scf.Min.Mixing.Weight      0.01      # default=0.001 scf.Max.Mixing.Weight      0.10      # default=0.40 scf.Mixing.History        5          # default=5 scf.Mixing.StartPulay      6          # default=6 scf.criterion            1.0e-10      # default=1.0e-6 (Hartree) #scf.restart                on # # MD or Geometry Optimization # MD.Type                    nomd      # Nomd|Opt|NVE|NVT_VS|NVT_NH MD.maxIter                    1        # default=1 MD.TimeStep                  1        # default=0.5 (fs) MD.Opt.criterion        1.0e-5        # default=1.0e-4 (Hartree/bohr) # # Band dispersion # Band.dispersion              on        # on|off, default=off # if <Band.KPath.UnitCell does not exist, #    the reciprical lattice vector is employed. Band.Nkpath                8 <Band.kpath 50    0.0000  0.0000  0.0000  -0.2718  0.2718  0.2718      Gamma  Sigma 50  -0.2718  0.2718  0.2718    0.2718  0.7282  -0.2718      Sigma  S 50    0.2718  0.7282  -0.2718    0.5000  0.5000  -0.5000      S      Z 50    0.5000  0.5000  -0.5000    0.0000  0.5000  0.0000      Z      N 50    0.0000  0.5000  0.0000    0.0000  0.0000  0.0000      N      Gamma 50    0.0000  0.0000  0.0000    0.5000  0.5000  -0.5000      Gamma  Z 50    0.5000  0.5000  -0.5000    0.0000  0.0000  0.5000      Z      X 50    0.0000  0.0000  0.5000    0.0000  0.0000  0.0000      X      Gamma Band.kpath> # # MO output # MO.fileout                      off  # on|off num.HOMOs                        1    # default=2 num.LUMOs                        1    # default=2 MO.Nkpoint                        2    # default=1 <MO.kpoint   0.0  0.0  0.0   0.0  0.0  0.2 MO.kpoint> # # DOS and PDOS # Dos.fileout                  on        # on|off, default=off Dos.Erange              -1.0  1.0    # default = -20 20 Dos.Kgrid              10  10  14      # default = Kgrid1 Kgrid2 Kgrid3 FermiSurfer.fileout          off

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Re: Problems in band calculation ( No.1 ) Date: 2023/02/20 02:32 Name: Yung-Ting Lee Following the parameters reported in Physical Review X, 5 (1), 011029 (2015), I recommend that you may check the points listed below. (1) the optimized lattice constant in the paper: a = b = 3.4824 angstroms, c = 11.8038 angstroms. Atoms.UnitVectors.Unit  Ang <Atoms.UnitVectors   3.4824  0.0000  0.0000   0.0000  3.4824  0.0000   0.0000  0.0000 11.8038 Atoms.UnitVectors> (2) According to Fig. 1(a) in Physical Review X, 5 (1), 011029 (2015), the number of atoms may be equal to 8 (not 4) and atomic positions in the input file are needed to be checked. Nonsymmorphic space group: I4_{1}md (No. 109) (3) Their basis set: Ta9.0-s2p2d2f1 and As9.0-s2p2d1 And, the energy cutoff may be not enough. (4) The higher energy cutoff ( > 150 Ryd ) may be required. In addition, an optimization for the TaAs crystal structure is needed. (5) MD.Type  RFC5    # for optimizing crystal structure You may update these parameters and perform optimization by OpenMX to get the optimized geometry structure and corresponding band structure in comparison with data in Physical Review X, 5 (1), 011029 (2015). Best regards, Yung-Ting Lee Re: Problems in band calculation ( No.2 ) Date: 2023/02/20 03:08 Name: Xinliang Huang  <xilhuang@foxmail.com> Hi， Thank you very much for your reply. I think this structure should be correct. With the same lattice constant, I have calculated it with first principles software such as VASP and ABACUS, and the results are consistent with those in the literature. The structure I used is primitive cell, while the structure given in the literature is conventional unit cell. At the same time, the Brillouin zone given in the literature corresponds to the lattice of the primitive cell. Other suggestions you give, such as base set: Ta  Ta9.0-s4p2d2f2  Ta_PBE19 As  As9.0-s2p2d2    As_PBE19 Ta  Ta9.0-s2p2d2f1  Ta_PBE19 As  As9.0-s2p2d1    As_PBE19 energycutoff: 600 The results are still not consistent with the literature. In addition, I also changed the parameters such as "scf. Kgrid", and still can't get the correct results. If you have time, can you run the code to see what the problem is. Thank you very much here. Best regards, Xinliang Huang Re: Problems in band calculation ( No.3 ) Date: 2023/02/20 17:17 Name: Yung-Ting Lee Following your reply and suggestion, I calculate the band structure of 2 TaAs crystal structures (without optimization), i.e. primitive cell and conventional cell. The TaAs band structure with primitive cell is similar to that in the paper. The parameters are listed below for your reference. --------------------------------------------------------------- 1. primitive cell: --------------------------------------------------------------- Species.Number  2 <Definition.of.Atomic.Species Ta  Ta9.0-s2p2d2f1 Ta_PBE19 As  As9.0-s2p2d1  As_PBE19 Definition.of.Atomic.Species> Atoms.Number  4 Atoms.SpeciesAndCoordinates.Unit  FRAC    # Ang|AU <Atoms.SpeciesAndCoordinates 1 As 0.417173041903  0.417173041903  0.000000000000 7.5 7.5 2 As 0.167173041903  0.667173041903  0.500000000000 7.5 7.5 3 Ta 0.999825801550  0.999825801550  0.000000000000 6.5 6.5 4 Ta 0.749825801550  0.249825801550  0.500000000000 6.5 6.5 Atoms.SpeciesAndCoordinates> Atoms.UnitVectors.Unit  Ang <Atoms.UnitVectors -1.731533000000  1.731533000000  5.867109000000   1.731533000000  -1.731533000000  5.867109000000   1.731533000000  1.731533000000  -5.867109000000 Atoms.UnitVectors> scf.energycutoff          600.0      # default=150 (Ry) scf.Kgrid                20 20 5      # means n1 x n2 x n3 --------------------------------------------------------------- 2. conventional cell: --------------------------------------------------------------- Species.Number  2 <Definition.of.Atomic.Species Ta  Ta9.0-s2p2d2f1 Ta_PBE19 As  As9.0-s2p2d1  As_PBE19 Definition.of.Atomic.Species> Atoms.Number  8 Atoms.SpeciesAndCoordinates.Unit  FRAC    # Ang|AU <Atoms.SpeciesAndCoordinates 1 As 0.500000000000  0.000000000000  0.167173041903 7.5 7.5 2 As 0.000000000000  0.000000000000  0.417173041903 7.5 7.5 3 As 0.000000000000  0.500000000000  0.667173041903 7.5 7.5 4 As 0.500000000000  0.500000000000  0.917173041903 7.5 7.5 5 Ta 0.000000000000  0.500000000000  0.249825801550 6.5 6.5 6 Ta 0.500000000000  0.500000000000  0.499825801550 6.5 6.5 7 Ta 0.500000000000  0.000000000000  0.749825801550 6.5 6.5 8 Ta 0.000000000000  0.000000000000  0.999825801550 6.5 6.5 Atoms.SpeciesAndCoordinates> Atoms.UnitVectors.Unit  Ang <Atoms.UnitVectors   3.4824  0.0000  0.0000   0.0000  3.4824  0.0000   0.0000  0.0000 11.8038 Atoms.UnitVectors> scf.energycutoff          600.0      # default=150 (Ry) scf.Kgrid                12 12 3      # means n1 x n2 x n3 --------------------------------------------------------------- In the conventional cell case, I guess that the unfolded TaAs band structure will be close to that in the primitive cell. Best regards, Yung-Ting Lee Re: Problems in band calculation ( No.4 ) Date: 2023/02/20 21:20 Name: Xinliang Huang  <xilhuang@foxmail.com> Thank you very much. According to your suggestion, I have calculated. From the result, the band is similar to the paper, but it is still not consistent with the paper at Sigma. After considering SOC, the result is better. I have calculated a lot of other materials before, using the default pseudopotential and parameters, and the results are good. I don't know whether this material is special enough to cause such results. Thank you very much for your suggestion. Thank you.

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