The ABINIT Users Mailing List ( CLOSED )

[Jian ZHOU <zjspam@gmail.com>]

Dear all,

I am trying to calculate the polarization of a BaTiO3 supercell with a
O atom vacancy.

Since It also have a inverse symmetry, so the polarization should be
zero. However, What I get is a large value.

I am a newbie of abinit and the following is my input file : 

----------------------------------------------------------------------------------------------------------
ndtset  4
udtset  2 2
acell1? 2*7.4962  15.155
acell2? 2*7.4962  15.155
prtden?1  1
ngkpt?1   4 4 2
nshiftk?1   4
shiftk?1    0.5 0.5 0.5
          0.5 0.0 0.0
          0.0 0.5 0.0
          0.0 0.0 0.5
rprim  1.0 0.0 0.0
       0.0 1.0 0.0
       0.0 0.0 1.0
kptopt?1  1
iscf?1    5
toldfe?1  1.0d-5
kptopt?2  2
ngkpt?2   4 4 8
iscf?2  -2
getden?2  -1
getwfk?2   -1
tolwfr?2   1.0d-16
nband?2  40
berryopt?2  1
nberry?2  1
bdberry?2   1  40
kberry?2  0 0 1
nbdbuf   0

#Common data
  diemac 4.0
  ecut 35.00
  ixc  1
  natom  9
 xred1?  0.0 0.0 0.0
  0.0000000000    0.0000000000    0.5000000000
 0.5000000000    0.5000000000    0.2500000000
 0.5000000000    0.5000000000    0.7500000000
 0.0000000000    0.5000000000    0.2500000000
 0.0000000000    0.5000000000    0.7500000000
 0.5000000000    0.0000000000    0.2500000000
 0.5000000000    0.0000000000    0.7500000000
 0.5000000000    0.5000000000    0.0000000000
xred2?  0.0  0.0  0.0
 0.0000000000000000  0.0000000000000000  0.5000000000000000
  0.5000000000000000  0.5000000000000000  0.2437203227287569
  0.5000000000000000  0.5000000000000000  0.7562796772712430
  0.0000000000000000  0.5000000000000000  0.2594752881088574
  0.0000000000000000  0.5000000000000000  0.7405247118911426
  0.5000000000000000  0.0000000000000000  0.2594752881088574
  0.5000000000000000  0.0000000000000000  0.7405247118911426
  0.5000000000000000  0.5000000000000000  0.0000000000000000
ntypat  3
  typat  1 1 2 2 3 3 3 3 3
  znucl  56 22 8
nstep  1000

----------------------------------------------------------------------------------------------------------

Since the calculation is quite slow, I set a low precision during 
calculation. 

The output polarization of the two dataset is:

..................
 Summary of the results
 Electronic Berry phase     4.178392957E-01
            Ionic phase     1.000000000E+00
            Total phase     1.417839296E+00
    Remapping in [-1,1]    -5.821607043E-01

           Polarization    -1.036001913E-02 (a.u. of charge)/bohr^2
           Polarization    -5.927460146E-01 C/m^2
...

 Summary of the results
 Electronic Berry phase     8.767717249E-01
            Ionic phase     1.000000000E+00
            Total phase     1.876771725E+00
    Remapping in [-1,1]    -1.232282751E-01

           Polarization    -2.192946513E-03 (a.u. of charge)/bohr^2
           Polarization    -1.254689099E-01 C/m^2
............................


Why the polarization is -5.927460146E-01 and  -1.254689099E-01 C/m^2
for the two structure? which should be 0.   Is there something wrong
in my input file?

by the way, can abinit v4.3.4 or v4.4.4 can be parallel during
calculating berry phase now?

Thank you in advance.

Best wishes,

Jian