Wannier centers and molecular dipoles

Ondrej Marsalek ondrej.... at gmail.com
Fri Nov 27 15:19:18 UTC 2009

Dear all,

I would like to get the Wannier centers and molecular dipoles in a
calculation in open boundary conditions. I have found two problems. I
attach two test calculations, together with the output on my machine.
They have two water molecules and differ only by the position of one
of them - in the "together" case they are both in the first octant,
while in the "separate" case they are more spread out.

1) The Wannier centers are wrapped into the cell from -L/2 to L/2.
This is a bother for display, but can in principle be resolved in
post-processing. Unfortunately, it looks like these positions are also
used for the assignment to molecules and the calculation of charges
and dipoles. The problem of course does not demonstrate if all the
centers fall into the first octant. This is the relevant part of the
output from the two calculations:

                           # molecule nr, charge, dipole vector, dipole (Debye)
     1    0.000000 -184.870480 -135.671636 -201.729105  305.415322
     2    0.000000 -132.712114 -197.946467 -134.405404  273.605778

                           # molecule nr, charge, dipole vector, dipole (Debye)
     1    0.000000    0.000000    0.000000    0.000000    0.000000
     2   -8.000000  129.208809  111.938778  101.509883  198.820177

2) Even when the centers are in the right places, the dipoles above do
not look right.

Can someone please confirm that they get the same results? If so, I
would like to ask for a fix, if possible.

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