[Pw_forum] Berry Phase calculation for gdir=1,2 in parallel

[Jess Kondor]

Dear All,

I have noticed that  calculation of polarization using Berry Phase method
and pwscf-4.0 doesn't work in parallel for gdir=1 and gdir=2. For example, I
took tetragonal phase of BaTiO3 with atomic displacements along 'x'
direction and (c,a,a) lattice vectors. For nprocs =1, it works fine:

VALUES OF POLARIZATION
                             ~~~~~~~~~~~~~~~~~~~~~~

        The calculation of phases done along the direction of vector 1
        of the reciprocal lattice gives the following contribution to
        the polarization vector (in different units, and being Omega
        the volume of the unit cell):

           P =   2.2164982  (mod  15.2155768)  (e/Omega).bohr

           P =   0.0051349  (mod   0.0352497)  e/bohr^2

           P =   0.2935730  (mod   2.0152882)  C/m^2

        The polarization direction is:  ( 1.00000 , 0.00000 , 0.00000 )


but for nprocs > 1 (for example, 16) it doesn't:

==================================================
                            POLARIZATION CALCULATION
                         !!! NOT THOROUGHLY TESTED !!!
               --------------------------------------------------

  error: translated G=  -0.2483941319370271         0.000000000000000
    0.000000000000000       with crystal coordinates           -1
0
            0  corresponds to ng=            0  but G(ng)=
   2.8071327799762095E-319    0.000000000000000
1.4927122354773060E-316
  probably because G_par is NOT a reciprocal lattice vector
  Possible choices as smallest  G_par:
  i=            1    G=    0.000000000000000         0.000000000000000
    0.000000000000000
  i=            2    G=    0.000000000000000         0.000000000000000
  -0.2508780732563974
  i=            3    G=    0.000000000000000         0.000000000000000
   0.2508780732563974
  i=            4    G=    0.000000000000000         0.000000000000000
  -0.5017561465127947
  i=            5    G=    0.000000000000000         0.000000000000000
   0.5017561465127947
  i=            6    G=   0.4967882638740543       -0.2508780732563974
    0.000000000000000
  i=            7    G=   0.4967882638740543       -0.2508780732563974
  -0.2508780732563974
.......

is there a way to solve this problem?

 Best regards,

-- 
=====================================
Jess Kondor, PhD student

PICYT, Av. Venustiano Carranza 2425-A,
San Luis Potosí 78210, México

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