[Pw_forum] DC & BEC

[Suza W]

Dear All,

Being an epitome of ferroelectric, BaTiO3 has extensively been
studied using PWSCF. However,  unfortunately, with several
standard available USPP, I encounter  following unphysical  results :


     Dielectric constant in cartesian axis

          (-8142842.391767483       0.000000000       0.000000000 )
          (       0.000000000-8142842.391767481       0.000000000 )
          (       0.000000000       0.000000000-8142842.391767476 )

          Effective charges (d Force / dE) in cartesian axis

           atom      1   Ba
      Ex  (    -1136.43937        0.00000        0.00000 )
      Ey  (        0.00000    -1136.43937        0.00000 )
      Ez  (        0.00000        0.00000    -1136.43937 )
           atom      2   Ti
      Ex  (    -1874.03151        0.00000        0.00000 )
      Ey  (        0.00000    -1874.03151        0.00000 )
      Ez  (        0.00000        0.00000    -1874.03151 )
           atom      3   O
      Ex  (      931.42284        0.00000        0.00000 )
      Ey  (        0.00000     1067.39482        0.00000 )
      Ez  (        0.00000        0.00000     1067.39482 )
           atom      4   O
      Ex  (     1067.39482        0.00000        0.00000 )
      Ey  (        0.00000      931.42284        0.00000 )
      Ez  (        0.00000        0.00000     1067.39482 )
           atom      5   O
      Ex  (     1067.39482        0.00000        0.00000 )
      Ey  (        0.00000     1067.39482        0.00000 )
      Ez  (        0.00000        0.00000      931.42284 )

Any suggestion for correcting these errors will be highly appreciated.
Here goes the input file which renders such a blunder.
 &system
    ibrav =  1,
    celldm(1) = 7.5589,
    nat = 5,
    ntyp=3,
    ecutwfc = 30.0,
        ecutrho = 240.0,
 /
 &electrons
    diagonalization = 'david'
    conv_thr =  1.0d-9
    mixing_beta = 0.7
 /
 &ions
 /
 &cell
 /
ATOMIC_SPECIES
 Ba  137.327       Ba.pbe-nsp-van.UPF
 Ti   47.867       Ti.pbe-sp-van_ak.UPF
 O    15.9994      O.pbe-van_ak.UPF
ATOMIC_POSITIONS (alat)
Ba  0.0  0.0  0.0
Ti  0.5  0.5  0.5
O  0.0  0.5  0.5
O  0.5  0.0  0.5
O  0.5  0.5  0.0
K_POINTS {automatic}
 8 8 8  1 1 1

Thanking you,
Yours sincerely,
Suza W
PhD Student
Department of Materials Science
Bangalore
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