[Pw_forum] A little energy gap (~ 0.2 eV) for graphene

[xirainbow]

    Please make sure that the Kpoint of the primitive grephene unit cell is
included in your kmesh.

On Mon, May 21, 2012 at 8:13 PM, Cao TF <tfcao at theory.issp.ac.cn> wrote:

> **
> 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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>


-- 
____________________________________
Hui Wang
School of physics, Fudan University, Shanghai, China
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