[Pw_forum] A little energy gap (~ 0.2 eV) for graphene
Cao TF
tfcao at theory.issp.ac.cn
Mon May 21 14:13:54 CEST 2012
Dear QE users,
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.
For scf.in
&CONTROL
title = 'graphene layer' ,
calculation = 'scf' ,
restart_mode = 'from_scratch' ,
outdir = './tmp' ,
pseudo_dir = '~pseudo' ,
prefix = 'graphene' ,
/
&SYSTEM
ibrav = 8 ,
a = 12.31 , b = 12.79312342 , c = 12.000 ,
nat = 60 ,
ntyp = 1 ,
occupations = 'smearing' ,
tot_charge = 0.0,
degauss = 0.02 ,
smearing = 'mp' ,
nspin = 2 ,
starting_magnetization(1) = 0.5 ,
ecutwfc = 30.0 ,
ecutrho = 300.0 ,
/
&ELECTRONS
conv_thr = 1.0d-8 ,
mixing_mode = 'local-TF' ,
mixing_beta = 0.7 ,
diagonalization = 'david' ,
/
ATOMIC_SPECIES
C 12.0107 C.pbe-rrkjus.UPF
ATOMIC_POSITIONS crystal
C 0.0000000 0.0000000 0.50000000
C 0.10000000 5.55555671E-02 0.50000000
C 0.10000000 0.16666667 0.50000000
C 0.0000000 0.22222224 0.50000000
C 0.0000000 0.33333334 0.50000000
C 0.10000000 0.38888890 0.50000000
C 0.10000000 0.50000000 0.50000000
C 0.0000000 0.55555558 0.50000000
C 0.0000000 0.66666669 0.50000000
C 0.10000000 0.72222227 0.50000000
C 0.10000000 0.83333337 0.50000000
C 0.0000000 0.88888896 0.50000000
C 0.20000000 0.0000000 0.50000000
C 0.30000001 5.55555671E-02 0.50000000
C 0.30000001 0.16666667 0.50000000
C 0.20000000 0.22222224 0.50000000
C 0.20000000 0.33333334 0.50000000
C 0.30000001 0.38888890 0.50000000
C 0.30000001 0.50000000 0.50000000
C 0.20000000 0.55555558 0.50000000
C 0.20000000 0.66666669 0.50000000
C 0.30000001 0.72222227 0.50000000
C 0.30000001 0.83333337 0.50000000
C 0.20000000 0.88888896 0.50000000
C 0.40000001 0.0000000 0.50000000
C 0.50000000 5.55555671E-02 0.50000000
C 0.50000000 0.16666667 0.50000000
C 0.40000001 0.22222224 0.50000000
C 0.40000001 0.33333334 0.50000000
C 0.50000000 0.38888890 0.50000000
C 0.50000000 0.50000000 0.50000000
C 0.40000001 0.55555558 0.50000000
C 0.40000001 0.66666669 0.50000000
C 0.50000000 0.72222227 0.50000000
C 0.50000000 0.83333337 0.50000000
C 0.40000001 0.88888896 0.50000000
C 0.60000002 0.0000000 0.50000000
C 0.70000005 5.55555671E-02 0.50000000
C 0.70000005 0.16666667 0.50000000
C 0.60000002 0.22222224 0.50000000
C 0.60000002 0.33333334 0.50000000
C 0.70000005 0.38888890 0.50000000
C 0.70000005 0.50000000 0.50000000
C 0.60000002 0.55555558 0.50000000
C 0.60000002 0.66666669 0.50000000
C 0.70000005 0.72222227 0.50000000
C 0.70000005 0.83333337 0.50000000
C 0.60000002 0.88888896 0.50000000
C 0.80000001 0.0000000 0.50000000
C 0.90000004 5.55555671E-02 0.50000000
C 0.90000004 0.16666667 0.50000000
C 0.80000001 0.22222224 0.50000000
C 0.80000001 0.33333334 0.50000000
C 0.90000004 0.38888890 0.50000000
C 0.90000004 0.50000000 0.50000000
C 0.80000001 0.55555558 0.50000000
C 0.80000001 0.66666669 0.50000000
C 0.90000004 0.72222227 0.50000000
C 0.90000004 0.83333337 0.50000000
C 0.80000001 0.88888896 0.50000000
K_POINTS automatic
8 8 1 0 0 0
For nscf.in
&CONTROL
title = 'graphene layer' ,
calculation = 'nscf' ,
restart_mode = 'from_scratch' ,
outdir = './tmp' ,
pseudo_dir = '/lustre/ISSP2/tfcao/pseudo' ,
prefix = 'graphene' ,
/
&SYSTEM
ibrav = 8 ,
a = 12.31 , b = 12.79312342 , c = 12.000 ,
nat = 60 ,
ntyp = 1 ,
occupations = 'tetrahedra' ,
tot_charge = 0.0,
nspin = 2 ,
starting_magnetization(1) = 0.5 ,
ecutwfc = 30.0 ,
ecutrho = 300.0 ,
/
&ELECTRONS
conv_thr = 1.0d-8 ,
mixing_mode = 'local-TF' ,
mixing_beta = 0.7 ,
diagonalization = 'david' ,
/
ATOMIC_SPECIES
C 12.0107 C.pbe-rrkjus.UPF
For dos.in
&inputpp
prefix = 'graphene' ,
outdir = './tmp' ,
Emin = -4.0 ,
Emax = 4.0 ,
DeltaE = 0.01 ,
fildos = graphene.dos ,
/
The accessory is the DOS I have got.
I am sorry for such a long file. I hope that you can give some suggestions.
======================================================================
Tengfei Cao, Research Laboratory for Computational Materials Sciences,
Instutue of Solid State Physics,the Chinese Academy of Sciences,
======================================================================
93,2 底端
1,2 顶端
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