[Pw_forum] Abnormally Dielectric constant and Effective charges

[ruizhi zhang]

Dear all
   
  I met a problem when I used ph.x to calculate Dielectric constant of BaTiO3. The Dielectric constants are abnormally large, and so do the effective charges. The output and input files are attached below. I have searched the forum and find someone fixed this problem by using denser k-grid. However, in my case this does not work. Even I use a 16x16x16 MP k-point, the problem also exsits. 
I also calculate effective charges of BaTiO3 using Berry Phase method, and the result is reasonable. It is not likely pseudopotentials are the problem, because Linear Response calculations of PbTiO3, BaZrO3, PbZrO3 all give reasonable results, and agree well with Berry Phase results.
   
  Really appreciate your help, thanks!
Ruizhi Zhang
  
Here are the input and output files
  bto.ph.out
.......
.......
 Dielectric constant in cartesian axis
   (  -10960.282004778       0.000000000       0.000000000 )
 (       0.000000000  -10960.282004778       0.000000000 )
 (       0.000000000       0.000000000  -10960.282004778 )
   Effective charges E-U in cartesian axis
    atom      1
 (      -30.52734        0.00000        0.00000 )
 (        0.00000      -30.52734        0.00000 )
 (        0.00000        0.00000      -30.52734 )
  atom      2
 (      -48.86837        0.00000        0.00000 )
 (        0.00000      -48.86837        0.00000 )
 (        0.00000        0.00000      -48.86837 )
  atom      3
 (       25.10465        0.00000        0.00000 )
 (        0.00000       27.75341        0.00000 )
 (        0.00000        0.00000       27.75341 )
  atom      4
 (       27.75341        0.00000        0.00000 )
 (        0.00000       27.75341        0.00000 )
 (        0.00000        0.00000       25.10465 )
  atom      5
 (       27.75341        0.00000        0.00000 )
 (        0.00000       25.10465        0.00000 )
 (        0.00000        0.00000       27.75341 )
.......
.......
  bto.scf.in
&control
    calculation  = 'scf'
    restart_mode = 'from_scratch'
    prefix = 'bto'
    pseudo_dir   = '/home/zrz/espresso-3.1.1/pseudo/'
    outdir       = '/home/zrz/phonon/bto.cub/tmp/'
 /
 &system
    ibrav=1
    celldm(1)=7.56
    nat=5
    ntyp=3
    ecutwfc=30
  /
 &electrons
    conv_thr = 1e-7
    mixing_beta=0.7
 /
&IONS
 /
ATOMIC_SPECIES
  Ba    137.33     Ba.vdb.UPF
  Ti    47.90      Ti.vdb.UPF
  O     15.9994    O.vdb.UPF
ATOMIC_POSITIONS
  Ba    0.000    0.000    0.000
  Ti    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 0 0 0
  
bto.ph.in
phonons of bto
&inputph
  tr2_ph=1.0d-12,
  prefix='bto',
  epsil = .true.
  trans = .false.
  amass(1)=137.33,
  amass(2)=47.90,
  amass(3)=15.9996
  outdir='/home/zrz/phonon/bto.cub/tmp/',
  fildyn='bto.dyn',
 /
0.0 0.0 0.0
   

 
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