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ewan

新虫 (正式写手)

应助: 0 (幼儿园)
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在线: 79.4小时
虫号: 1349788
注册: 2011-07-19
性别: GG
专业: 凝聚态物性 II ：电子结构

[交流] LiF能带结构计算的困惑

大家好！小弟之前没有接触过能带计算，最近使用siesta计算64个原子LiF的能带结构（2*2*2的Supercell），对交换关联泛函是采用LDA，计算沿布里渊区的高对称轴Γ->X->W->Γ计算能带结构，k sampling只有一个Г点，并且MeshCutoff =300.0 Ry。我有点不能理解算出来的结果（如下图），从E（k）似乎有两个带隙（LiF带隙的实验值是14 eV），请问哪个是真正的带隙？最好是指明这两个带隙是如何产生的？(Fermi能级已经移至0 eV处)。如果哪位需要图的源文件的话，可以私聊啊！
      附有能带图两张（第一张是的能量范围是-22~6 eV，第二张是-2~-6 eV）和siesta计算的输入文件。

#######################################################################################
SystemName       bulk.LiF
SystemLabel       bulk_LiF

NumberOfAtoms    8
NumberOfSpecies    2

%block ChemicalSpeciesLabel
1 3 Li
2 9 F
%endblock ChemicalSpeciesLabel

# basis
PAO.BasisSize    DZP
PAO.EnergyShift    200 meV

LatticeConstant 4.04 Ang # Lattice constant alat
%block LatticeVectors             # Lattice vectors, in units of latticeconstant
2.0    0.0    0.0
0.0    2.0    0.0
0.0    0.0    2.0
%endblock LatticeVectors

%block SuperCell
2 0 0 0.0
0 2 0 0.0
0 0 2 0.0
%endblock SuperCell

%block kgrid_Monkhorst_Pack
1 0 0 0.0
0 1 0 0.0
0 0 1 0.0
%endblock kgrid_Monkhorst_Pack

BandLinesScale  ReciprocalLatticeVectors
%block BandLines
1    0.0 0.0 0.0    # Gamma-point
20 0.5 0.0 0.5    # X-point
30 0.5 0.25  0.75 # W-point
30 0.0 0.0 0.0    # Gamma-point
%endblock BandLines

%block  ProjectedDensityOfStates
-20 10 0.1  300 eV
%endblock ProjectedDensityOfStates

MeshCutoff       300.0 Ry

# SCF options
MaxSCFIterations    100          # Maximum number of SCF iter
DM.NumberPulay       3          # One Pulay every 3 iter
DM.MixingWeight    0.35       # New DM amount for next SCF cycle
DM.Tolerance       5.d-4       # Tolerance in maximum difference

SolutionMethod       diagon       # OrderN or Diagon
OccupationFunction FD
ElectronicTemperature  25 meV    # Temp. for Fermi smearing

# exchange-correlation functional
XC.functional LDA
XC.authors CA

# structural infomation
AtomCoorFormatOut Ang

# output information
WriteCoorXmol T
WriteMDXmol T
WriteForces T

WriteKpoints          .true.
WriteEigenvalues       .true.
WriteKbands          .true.
WriteBands             .true.
WriteMullikenPop       1

# options for MD
MD.MaxForceTol       0.01 eV/Ang
MD.TypeOfRun CG
MD.NumCGSteps 400
MD.Broyden.History.Steps 6
MD.Broyden.Initial.Inverse.Jacobian 1.0

# options for continue
# MD.UseSaveCG T                      # neccessary!
# MD.UseSaveXV T                      # neccessary!
# DM.UseSaveDM       true          # to use continuae..ion files

AtomicCoordinatesFormat Ang
%block AtomicCoordinatesAndAtomicSpecies
  -5.963747    -2.022693    -2.026392             1
  -6.051639    -5.949852    -2.013945             2
  -2.147364    -2.056847    -2.009531             2
  -2.039835    -5.953723    -2.024337             1
  -6.085698    -1.925561    2.008577             2
  -5.941415    -5.910826    2.052174             1
  -2.040599    -2.032355    2.028040             1
  -2.129653    -6.096888    2.008118             2
%endblock AtomicCoordinatesAndAtomicSpecies

Graph1.png