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<div>Dear QE users,
<BR>
I have calculated the density of states (DOS) of pure graphene. The supercell used in my work is a rectangular cell containing 60 carbon atoms. But something has puzzled me greatly. There is always a little energy gap (~0.2 eV) in the DOS, which contracts with the fact that graphene is zero gap semiconductor. Although I have change many parameters. This problem has not been solved. Here I give the input file and I will be greatly appreciated if you can give me some suggestions.
<BR>
For scf.in
<BR>
&CONTROL
<BR>
title = 'graphene layer' ,
<BR>
calculation = 'scf' ,
<BR>
restart_mode = 'from_scratch' ,
<BR>
outdir = './tmp' ,
<BR>
pseudo_dir = '~pseudo' ,
<BR>
prefix = 'graphene' ,
<BR>
/
<BR>
&SYSTEM
<BR>
ibrav = 8 ,
<BR>
a = 12.31 , b = 12.79312342 , c = 12.000 ,
<BR>
nat = 60 ,
<BR>
ntyp = 1 ,
<BR>
occupations = 'smearing' ,
<BR>
tot_charge = 0.0,
<BR>
degauss = 0.02 ,
<BR>
smearing = 'mp' ,
<BR>
nspin = 2 ,
<BR>
starting_magnetization(1) = 0.5 ,
<BR>
ecutwfc = 30.0 ,
<BR>
ecutrho = 300.0 ,
<BR>
/
<BR>
&ELECTRONS
<BR>
conv_thr = 1.0d-8 ,
<BR>
mixing_mode = 'local-TF' ,
<BR>
mixing_beta = 0.7 ,
<BR>
diagonalization = 'david' ,
<BR>
/
<BR>
ATOMIC_SPECIES
<BR>
C 12.0107 C.pbe-rrkjus.UPF
<BR>
ATOMIC_POSITIONS crystal
<BR>
C 0.0000000 0.0000000 0.50000000
<BR>
C 0.10000000 5.55555671E-02 0.50000000
<BR>
C 0.10000000 0.16666667 0.50000000
<BR>
C 0.0000000 0.22222224 0.50000000
<BR>
C 0.0000000 0.33333334 0.50000000
<BR>
C 0.10000000 0.38888890 0.50000000
<BR>
C 0.10000000 0.50000000 0.50000000
<BR>
C 0.0000000 0.55555558 0.50000000
<BR>
C 0.0000000 0.66666669 0.50000000
<BR>
C 0.10000000 0.72222227 0.50000000
<BR>
C 0.10000000 0.83333337 0.50000000
<BR>
C 0.0000000 0.88888896 0.50000000
<BR>
C 0.20000000 0.0000000 0.50000000
<BR>
C 0.30000001 5.55555671E-02 0.50000000
<BR>
C 0.30000001 0.16666667 0.50000000
<BR>
C 0.20000000 0.22222224 0.50000000
<BR>
C 0.20000000 0.33333334 0.50000000
<BR>
C 0.30000001 0.38888890 0.50000000
<BR>
C 0.30000001 0.50000000 0.50000000
<BR>
C 0.20000000 0.55555558 0.50000000
<BR>
C 0.20000000 0.66666669 0.50000000
<BR>
C 0.30000001 0.72222227 0.50000000
<BR>
C 0.30000001 0.83333337 0.50000000
<BR>
C 0.20000000 0.88888896 0.50000000
<BR>
C 0.40000001 0.0000000 0.50000000
<BR>
C 0.50000000 5.55555671E-02 0.50000000
<BR>
C 0.50000000 0.16666667 0.50000000
<BR>
C 0.40000001 0.22222224 0.50000000
<BR>
C 0.40000001 0.33333334 0.50000000
<BR>
C 0.50000000 0.38888890 0.50000000
<BR>
C 0.50000000 0.50000000 0.50000000
<BR>
C 0.40000001 0.55555558 0.50000000
<BR>
C 0.40000001 0.66666669 0.50000000
<BR>
C 0.50000000 0.72222227 0.50000000
<BR>
C 0.50000000 0.83333337 0.50000000
<BR>
C 0.40000001 0.88888896 0.50000000
<BR>
C 0.60000002 0.0000000 0.50000000
<BR>
C 0.70000005 5.55555671E-02 0.50000000
<BR>
C 0.70000005 0.16666667 0.50000000
<BR>
C 0.60000002 0.22222224 0.50000000
<BR>
C 0.60000002 0.33333334 0.50000000
<BR>
C 0.70000005 0.38888890 0.50000000
<BR>
C 0.70000005 0.50000000 0.50000000
<BR>
C 0.60000002 0.55555558 0.50000000
<BR>
C 0.60000002 0.66666669 0.50000000
<BR>
C 0.70000005 0.72222227 0.50000000
<BR>
C 0.70000005 0.83333337 0.50000000
<BR>
C 0.60000002 0.88888896 0.50000000
<BR>
C 0.80000001 0.0000000 0.50000000
<BR>
C 0.90000004 5.55555671E-02 0.50000000
<BR>
C 0.90000004 0.16666667 0.50000000
<BR>
C 0.80000001 0.22222224 0.50000000
<BR>
C 0.80000001 0.33333334 0.50000000
<BR>
C 0.90000004 0.38888890 0.50000000
<BR>
C 0.90000004 0.50000000 0.50000000
<BR>
C 0.80000001 0.55555558 0.50000000
<BR>
C 0.80000001 0.66666669 0.50000000
<BR>
C 0.90000004 0.72222227 0.50000000
<BR>
C 0.90000004 0.83333337 0.50000000
<BR>
C 0.80000001 0.88888896 0.50000000
<BR>
K_POINTS automatic
<BR>
8 8 1 0 0 0
<BR>
For nscf.in
<BR>
&CONTROL
<BR>
title = 'graphene layer' ,
<BR>
calculation = 'nscf' ,
<BR>
restart_mode = 'from_scratch' ,
<BR>
outdir = './tmp' ,
<BR>
pseudo_dir = '/lustre/ISSP2/tfcao/pseudo' ,
<BR>
prefix = 'graphene' ,
<BR>
/
<BR>
&SYSTEM
<BR>
ibrav = 8 ,
<BR>
a = 12.31 , b = 12.79312342 , c = 12.000 ,
<BR>
nat = 60 ,
<BR>
ntyp = 1 ,
<BR>
occupations = 'tetrahedra' ,
<BR>
tot_charge = 0.0,
<BR>
nspin = 2 ,
<BR>
starting_magnetization(1) = 0.5 ,
<BR>
ecutwfc = 30.0 ,
<BR>
ecutrho = 300.0 ,
<BR>
/
<BR>
&ELECTRONS
<BR>
conv_thr = 1.0d-8 ,
<BR>
mixing_mode = 'local-TF' ,
<BR>
mixing_beta = 0.7 ,
<BR>
diagonalization = 'david' ,
<BR>
/
<BR>
ATOMIC_SPECIES
<BR>
C 12.0107 C.pbe-rrkjus.UPF
<BR>
For dos.in
<BR>
&inputpp
<BR>
prefix = 'graphene' ,
<BR>
outdir = './tmp' ,
<BR>
Emin = -4.0 ,
<BR>
Emax = 4.0 ,
<BR>
DeltaE = 0.01 ,
<BR>
fildos = graphene.dos ,
<BR>
/
<BR>
The accessory is the DOS I have got.
<BR>
I am sorry for such a long file. I hope that you can give some suggestions.
<BR>
======================================================================
<BR>
Tengfei Cao, Research Laboratory for Computational Materials Sciences,
<BR>
Instutue of Solid State Physics,the Chinese Academy of Sciences,
<BR>
<BR>
======================================================================
<BR>
<BR>
<BR>
<BR>
<BR>
<BR>
<BR>
93,2 底端
<BR>
1,2 顶端
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