[Pw_forum] Graphene_fixed calculation

[Higuchi Toshiharu]

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 

 

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Toshiharu Higuchi

University of Tsukuba/ Japan

E-Mail:  <mailto:toshihigu at r7.dion.ne.jp> toshihigu at r7.dion.ne.jp

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