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How does openMX decide the number of eigenvalues on a Kpoint (number of bands) and valance bands Date: 2023/05/18 11:01 Name: Tao Zhang   <zhangtao_scu@outlook.com> As We Know, When we calculate the band structure of semiconductor by VASP, We can clearly know that the number of band is decided by NBANDS paramters and the number of valence band is decided by total electrons of the system. Therefore, How does OpenMX define the number of bands and valence band? For example, I have tried to understand the reason why the valence band is 28 and the total number of all bands is 130 in In2Se3 monolayer. First, according to the electrons, In possesses13 electrons, while Se possesses 6 electrons. However (13*2+6*3)/2=22, it is not equal to 28. Second, According to number of basis, (3*1+2*3+5*2+7*1)*5=130. This is equal to the total number of all bands. it seems indicate that the number of whole bands are decided by the number of basis functions. here is the dat file: Species.Number                    2 <Definition.of.Atomic.Species   Se    Se7.0-s3p2d2f1      Se_PBE19   In    In7.0-s3p2d2f1      In_PBE19 Definition.of.Atomic.Species> Atoms.Number                      5 Atoms.SpeciesAndCoordinates.Unit  FRAC <Atoms.SpeciesAndCoordinates   1    In    0.6666670  0.3333330  0.5803360    6.5  6.5   2    In    0.3333330  0.6666670  0.4223670    6.5  6.5   3    Se    0.6666670  0.3333330  0.4849070    3.0  3.0   4    Se    0.0000000  0.0000000  0.6270930    3.0  3.0   5    Se    0.0000000  0.0000000  0.3729070    3.0  3.0 Atoms.SpeciesAndCoordinates> Atoms.UnitVectors.Unit            Ang <Atoms.UnitVectors     4.1098870    0.0000000    0.0000000     -2.0549435    3.5592665    0.0000000     0.0000000    0.0000000    26.8163070 Atoms.UnitVectors> scf.XcType                    GGA-PBE scf.SpinPolarization          off scf.ElectronicTemperature    400.0 scf.energycutoff              300.0 scf.maxIter                  100 scf.EigenvalueSolver          band scf.Kgrid                    15  15  1 scf.Mixing.Type              rmm-diisk scf.Init.Mixing.Weight        0.05 scf.Min.Mixing.Weight        0.01 scf.Max.Mixing.Weight        0.30 scf.Mixing.History            25 scf.Mixing.StartPulay        15 scf.criterion                1.0e-7 Here is part of Band file: 130  0  -0.184138965809156 0.809004898628725  0.467079202387699 -0.000000000000000  0.000000000000000  0.934158404775398  0.000000000000000  0.000000000000000 -0.000000000000000  0.123988687771605 3 23  0.000000000000000  0.000000000000000  0.000000000000000  0.500000000000000 -0.000000000000000  0.000000000000000  G M 20  0.500000000000000 -0.000000000000000  0.000000000000000  0.333333000000000  0.333333000000000  0.000000000000000  M K 27  0.333333000000000  0.333333000000000  0.000000000000000  0.000000000000000  0.000000000000000  0.000000000000000  K G 130  0.000000000000000  0.000000000000000  0.000000000000000 -0.743948322630179 -0.738285346989708 -0.737776282927199 -0.734825666620242 -0.734491634848795 -0.708607096909747 -0.708110218578062 -0.707162825661274 -0.704607954076597 -0.704264731045695 -0.686429617119123 -0.657580811852788 -0.627134269407600 -0.398398033902845 -0.322485025129069 -0.251906174427737 -0.251884779867368 -0.235554229450423 -0.213994103553884 -0.213986512466368 -0.205775670822113 -0.205772864477724 -0.170276123324929 -0.129340111206383 -0.068121027741015 -0.026600894452358 -0.026546276938462 -0.019074746136304  0.006043990636892  0.006061794740282  0.101746303774972  0.128244764274416  0.128484103095418  0.130507953674968  0.153417357585264  0.153522995025992  0.153559359489761  0.177448592276649  0.218549072037596  0.221964883788078  0.222119212109013  0.243594947683203  0.243717830248618  0.259870390126173  0.310020928372860  0.310160286391369  0.332480565337071  0.349383407541476  0.378135772372166  0.378236197093949  0.417584753462828  0.473121637502784  0.473218235448996  0.504546802231605  0.558161590685054  0.558303763025724  0.584147781048860  0.605518955412024  0.667635089313242  0.667714710479672  0.669330578594024  0.696979272706494  0.697128722324628  0.754176228742105  0.754225216358005  0.771748110347358  0.771824086615763  0.817054685026278  0.817156965319767  0.821063129448766  0.821115109059149  0.838574183034673  0.857429252817355  0.857456201541590  0.860062052378233  0.868021227943927  0.903121627883581  0.903148784286576  0.921498075490603  0.951099174409450  0.951220687296505  0.963776258296178  1.024133258051537  1.036215067171727  1.047715961436227  1.047746834788796  1.053747335752052  1.053831739122370  1.106634957061160  1.106662402449483  1.125150005863254  1.168449481941864  1.175758183029660  1.181924887044812  1.181956455325523  1.209821190874372  1.209854746930954  1.262906099166084  1.272288692980448  1.292780829843237  1.292800545519885  1.301098629563117  1.341691597261722  1.352470035734713  1.366219545295958  1.366289163118549  1.369393732912458  1.461437010317124  1.461539497164619  1.462793413863417  1.513292597113943  1.604547631040132  1.841986858063811  1.842064878653206  1.994185955929436  2.150580301449579  2.301981489314372  2.302036543387316  2.468883889776677  2.503047572692174  2.503072120448994  2.645417022067428  2.645461328889752  2.772678229644461  2.847234820114398  3.526905302939155  3.526938508238101  3.771394923586365  3.771403230674837  4.764706295936346 130  0.022727272727273  0.000000000000000  0.000000000000000

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Re: How does openMX decide the number of eigenvalues on a Kpoint (number of bands) and valance bands ( No.1 ) Date: 2023/05/18 12:46 Name: Naoya Yamaguchi Hi, As for the first question, the number of the occupied bands has to be 22 in this case. Where did you find "28"? >Second, According to number of basis, (3*1+2*3+5*2+7*1)*5=130. This is equal to the total number of all bands. it seems indicate that the number of whole bands are decided by the number of basis functions. Yes. Regards, Naoya Yamaguchi Re: How does openMX decide the number of eigenvalues on a Kpoint (number of bands) and valance bands ( No.2 ) Date: 2023/05/18 12:52 Name: Naoya Yamaguchi Dear Tao Zhang, I've understood what you mean about "28". Since the Fermi level is not set to 0 eV, you should compare the energy eigenvalues with the chemical potential of -0.184138965809156. You can find that the number of valence bands is 22 from that. Regards, Naoya Yamaguchi Re: How does openMX decide the number of eigenvalues on a Kpoint (number of bands) and valance bands ( No.3 ) Date: 2023/05/18 17:44 Name: Tao Zhang  <zhangtao_scu@outlook.com> Hi Oh, I get iy. Sorry for I forget that. many thanks for your guidance. Best regards, Tao

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