[Pw_forum] Graphene_fixed calculation

[siddheshwar chopra]

Dear Toshiharu,
I am also working on Graphene; but not using QE. I am a new QE user. Could
you please help me in adding desired SUPERCELL for graphene using PWGUI. I
understand the :Atomic Species and Atomic positions from your i/p file, but
how to add a supercell?
Please help.


On Tue, May 27, 2014 at 2:12 PM, Higuchi Toshiharu
<toshihigu at r7.dion.ne.jp>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
>
>
> **************************************************************************************
>
>
>
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>



-- 
*Dr. Siddheshwar chopra,*


*M.Sc., Ph.D (Physics)Assistant Professor (Physics),*
*Amity University, Noida, India.*
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