[Pw_forum] Berry Phase

[Srijan Kumar Saha]

Dear QE USERS,

I am facing the following error  during polarisation computation with Berry
Phase method;
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
     from c_phase : error #         1
     Polarization only for insulators and no empty bands
 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%

     stopping ...

even though, I have fixed  the occupations which is needed for an insulator
?

Does this mean that Berry Phase calculation in QE is only for
BAND-INSULATOR, and not for any
other insulator ? Does this mean, if one has odd number of electrons in a
unit-cell, then QE can not
treat the system as insulator, even one forces QE to do so by specifying
occupation "fixed" ?

Looking forward to your kind reply.

Input files are appended below :
 &control
    calculation  = 'scf'
    restart_mode = 'from_scratch'
    pseudo_dir   = '/home/pseudo/'
    outdir       = './'
    tstress=.true.
    tprnfor=.true.
 /
 &system
    ibrav=1
    celldm(1)=6.84,
    nat=5
    ntyp=3
    ecutwfc=50.0,
    ecutrho=400.0,
    occupations='fixed'
    tot_magnetization=3.0
    nspin=2,
 /
 &electrons
    conv_thr = 1e-7,
 /
ATOMIC_SPECIES
   Bi   209.0      Bi.pbe-d-mt.UPF
   Fe    55.85     Fe.pbe-nd-rrkjus.UPF
   O     16.00     O.pbe-mt.UPF
ATOMIC_POSITIONS
  Bi    0.000    0.000    0.010
  Fe    0.500    0.500    0.500
  O     0.000    0.500    0.500
  O     0.500    0.500    0.000
  O     0.500    0.000    0.500
K_POINTS {automatic}
  4 4 4 1 1 1

BerryPhase.in:

 &control
    calculation   = 'nscf'
    pseudo_dir    = '/home/pseudo/'
    outdir        = './'
    lberry        = .true.
    gdir          = 3
    nppstr        = 7
 /
 &system
    ibrav         = 1
    celldm(1)     = 6.84
    nat           = 5
    ntyp          = 3
    ecutwfc       = 50.0
    ecutrho=400.0,
    tot_magnetization=3.0,
    nspin=2
    occupations='fixed'
 /
 &electrons
 /
 ATOMIC_SPECIES
   Bi   209.0      Bi.pbe-d-mt.UPF
   Fe    55.85     Fe.pbe-nd-rrkjus.UPF
   O     16.00     O.pbe-mt.UPF
ATOMIC_POSITIONS
  Bi    0.000    0.000    0.010
  Fe    0.500    0.500    0.500
  O     0.000    0.500    0.500
  O     0.500    0.500    0.000
  O     0.500    0.000    0.500
K_POINTS {automatic}
  4 4 7  1 1 1

Thanking you and with my best regards,

Srijan Kumar
R&D Associate,
Indian Institute of Science,
India, 560012
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