Top Page > Browsing

SiC polymorphic DOS does not match with VASP Date: 2022/08/22 11:27 Name: IK For the "Computed" cif of the SiC polymorphs listed in the Materials project at https://materialsproject.org/materials/mp-624397 , VASP (Materials project) shows it as an insulator while OpenMX shows a metal. The input of OpenMX is shown below. 0.03 eV Gaussian broadening was used for DosMain. System.CurrentDirectory ./ System.Name tmp DATA.PATH /opt/openmx3.9/DFT_DATA19 level.of.fileout 1 Species.Number 2 <Definition.of.Atomic.Species Si Si7.0-s2p2d1 Si_PBE19 C C6.0-s2p2d1 C_PBE19 Definition.of.Atomic.Species> Atoms.Number 22 Atoms.SpeciesAndCoordinates.Unit Ang <Atoms.SpeciesAndCoordinates 1 Si 75.6039805720998 4.213848543174069 2.437905328148616 2.0 2.0 2 Si 30.24353821516888 1.6856478783796807 0.9752248810036259 2.0 2.0 3 Si 15.124305542756785 0.842965309440123 0.48769422969828613 2.0 2.0 4 Si 45.362438240345256 2.528311906958545 1.462744805856969 2.0 2.0 5 Si 35.28497339608781 1.9666363148597217 1.1377896242363879 2.0 2.0 6 Si 50.405120848398134 2.8093698697911846 1.625349773284718 2.0 2.0 7 Si 0.002411692458953003 0.0001344176150229486 7.776677697453233e-05 2.0 2.0 8 Si 68.04390684594468 3.792481765708338 2.194125253624451 2.0 2.0 9 Si 25.201936710632094 1.404650171719293 0.8126547745448656 2.0 2.0 10 Si 60.483749957980585 3.3711103531524325 1.950342497487287 2.0 2.0 11 Si 10.081872420130706 0.5619212518780037 0.32509730710953466 2.0 2.0 12 C 66.14499010085044 3.6866441166933717 2.1328933024025036 2.0 2.0 13 C 8.188028545381163 0.4563663433636034 0.2640289342805338 2.0 2.0 14 C 73.7050638270056 4.108010894159103 2.376673376926669 2.0 2.0 15 C 13.231043800669749 0.7374428465569351 0.4266446281602791 2.0 2.0 16 C 23.30842548311827 1.2991138035655858 0.7515971281678613 2.0 2.0 17 C 28.351523900215785 1.5801949418490908 0.9142155036606057 2.0 2.0 18 C 58.58483321288636 3.265272704137468 1.8891105462653395 2.0 2.0 19 C 48.51152645907538 2.703828866547304 1.5642894452947147 2.0 2.0 20 C 81.26497122954287 4.529368401444488 2.6204480882248355 2.0 2.0 21 C 33.39137900676506 1.861095311615841 1.0767292962463844 2.0 2.0 22 C 43.468927012831436 2.422775538804838 1.4016871594799647 2.0 2.0 Atoms.SpeciesAndCoordinates> Atoms.UnitVectors.Unit Ang <Atoms.UnitVectors 27.8355398 0.0 0.0 27.663134295508943 3.0932631485246675 0.0 27.663134833904955 1.5418270246804564 2.6816129991218047 Atoms.UnitVectors> scf.Kgrid 8 8 8 scf.maxIter 100 scf.Mixing.History 25 scf.Mixing.StartPulay 15 scf.ElectronicTemperature 300 scf.energycutoff 200 scf.Init.Mixing.Weight 0.05 scf.Min.Mixing.Weight 0.01 scf.Max.Mixing.Weight 0.3 scf.criterion 4e-08 scf.XcType GGA-PBE scf.EigenvalueSolver band scf.Mixing.Type rmm-diisk scf.Hubbard.U Off scf.stress.tensor On level.of.stdout 1 HS.fileout On scf.SpinPolarization off Dos.fileout on Dos.Erange -10.0 10.0 Dos.Kgrid 16 16 16 To improve the accuracy of OpenMX, I varied the cutoff energy from 200->300->400->500 and used s3p3d2 instead of s2p2d1, but the qualitative results did not change. In all cases, the SCF itself converged. Is there anything else I should change in the calculation conditions?

Page: [1]

Re: SiC polymorphic DOS does not match with VASP ( No.1 ) Date: 2022/08/24 14:11 Name: T. Ozaki Hi, For such a slimline unit cell with very sharp angles between unit cell vectors, the convergence of the numerical integration by the regular mesh tends to be quite slow. To check the convergence, I increased scf.energycutoff to 2000 Ryd., and got a proper gap of ~ 2 eV, being comparable to that shown at https://materialsproject.org/materials/mp-624397 On the other hand, for the conventional cell including 66 atoms, it turned out that the scf.energycutof of 220 Ryd. is enough to get the proper gap, which implies that the convergence for scf.energycutof strongly depends on the shape of the unit cell. So, I wonder that this is a good example reminding us that we need to be careful when a slimline unit cell with very sharp angles is treated. Regards, TO

Page: [1]