Dear Toshiharu Higuchi,
How did you determine the band gap? Do you have a k point exactly at the
point K of the Brillouin zone? I would guess no, and like I mentioned
recently, I do not think that shifting the Monkhorst-Pack k point grid
away from the Gamma (or Gamma-bar in two dimensions) point is a good idea.
Greetings,
apsi
-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-=*=-
Ari Paavo Seitsonen / Ari.P.Seitsonen at iki.fi / http://www.iki.fi/~apsi/
Institut f?r Chemie der Universit?t Z?rich, CH-8057 Z?rich
Tel: +41 44 63 54 497 / Mobile: +41 79 71 90 935
On Tue, 27 May 2014, Higuchi Toshiharu wrote:
>
> Dear Quantum-ESRESSO users,
>
> I would like to calculate the local density of state of graphene and graphene
>
> related materials.
>
> Using the following pw.in file, I calculated the scf under ?occupation =
> fixed?,
>
> and get the HOMO = -0.8642 eV, and LUMO = -0.6635 eV. This results indicate
>
> that this graphene is an insulator having a band gap of 0.2007 eV.
>
> However, this model is half-metal having a band gap of 0.0 eV, if I
> calculated by
>
> this process: (1)SCF (smearing) -> nscf (tetrahedra) -> ProjWFC.
>
> Why will it become the error when I set ?occupation = fixed??
>
> I would really appreciate if you teach me.
>
> ******************************************************************
>
> &CONTROL
>
> ?????????????????????? title = 'Graphene_1A2' ,
>
> ???????????????? calculation = 'scf' ,
>
> ??????????????? restart_mode = 'from_scratch' ,
>
> ? ????????????????????outdir = '/home/user/tmp/' ,
>
> ????????????????? pseudo_dir =
> '/home/user/espresso-5.0.1/espresso-5.0.1/pseudo/' ,
>
> ????????????????????? prefix = 'Graphene_1A2' ,
>
> ?????????????????? verbosity = 'high' ,
>
> /
>
> &SYSTEM
>
> ?????????????????????? ibrav = 4,
>
> ?????????????????? celldm(1) = 4.6595,
>
> ?????????????????? celldm(3) = 4.0571,
>
> ???????????????????????? nat = 2,
>
> ??????????????????????? ntyp = 1,
>
> ???????????????????? ecutwfc = 40 ,
>
> ???????????????????? ecutrho = 200 ,
>
> ??????????????????????? nbnd = 150,
>
> ???????????????? occupations = 'fixed' ,
>
> ???????????????????? degauss = 0.02 ,
>
> ??????????????????? smearing = 'gaussian' ,
>
> ??????????? exxdiv_treatment = 'gygi-baldereschi' ,
>
> /
>
> &ELECTRONS
>
> ??????????? electron_maxstep = 100,
>
> ??????????????????? conv_thr = 1.D-8 ,
>
> /
>
> ATOMIC_SPECIES
>
> ??? C?? 12.01100? C.pz-rrkjus.UPF
>
> ATOMIC_POSITIONS angstrom
>
> ????C????? 0.000000000??? 0.000000000??? 0.000000000???
>
> ????C????? 1.232850116??? 0.706423116??? 0.000000000???
>
> K_POINTS automatic
>
> ??40 40 1?? 1 1 1
>
> ?
>
> **************************************************************************************
>
> Toshiharu Higuchi
>
> University of Tsukuba/ Japan
>
> E-Mail: toshihigu at r7.dion.ne.jp
>
> **************************************************************************************
>
> ?
>
>
>
