Dear Dr. Seitsonen, Thank you very much for your kindness reply. I changed the k points, however the band gap was not 0 eV. If you have any comment, please teach me.
k-point(automatic) HOMO LUMO band gap 40 40 1 1 1 1 -0.8642 eV -0.6635 eV 0.2007 eV 40 40 1 0 0 0 -0.9682 eV -0.5618 eV 0.4064 eV 40 40 1 0 0 1 -0.9686 eV -0.5622 eV 0.4064 eV (band gap = LUMO - HOMO) *********************************************** Dr. Toshiharu Higuchi University of Tsukuba/ Japan E-Mail: toshihigu at r7.dion.ne.jp *********************************************** -----Original Message----- From: pw_forum-bounces at pwscf.org [mailto:[email protected]] On Behalf Of Ari P Seitsonen Sent: Tuesday, May 27, 2014 7:08 PM To: PWSCF Forum Subject: Re: [Pw_forum] Graphene_fixed calculation 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 > > ********************************************************************** > **************** > > > > >
