[CP2K:4726] difference between wannier total dipole and berry total dipole

[hut... at pci.uzh.ch]

Hi

Berry phase total dipoles are calculated from the determinant
of the exp(-ikr) operator. For the Wannier total dipole first
localized orbitals are calculated. Then the exp(-ikr) operator
matrices are transformed into this new basis. Finally, the
determinant is approximated by the product of the diagonal elements.
This allows to sparate the dipole into molecular contributions.

The two ways of calculation should give very similar total dipoles.
Are you sure that you compare values with the same units?
There is also the problem of 'branch', meaning that the calculated dipole
is given +/- 2Pi/L.

regards

Juerg Hutter



--------------------------------------------------------------
Juerg Hutter                         Phone : ++41 44 635 4491
Physical Chemistry Institute   FAX   : ++41 44 635 6838
University of Zurich               E-mail:  hut... at pci.uzh.ch
Winterthurerstrasse 190
CH-8057 Zurich, Switzerland
---------------------------------------------------------------

-----cp... at googlegroups.com wrote: -----
To: cp... at googlegroups.com
From: labicia 
Sent by: cp... at googlegroups.com
Date: 10/24/2013 10:54AM
Subject: [CP2K:4726] difference between wannier total dipole and berry total dipole

Good morning!

We are kind of new on this subject: may somebody tell us in a few words the difference between the wannier total dipole and berry total dipole.
Or at least give us some reference to document ourselves?

We are simulating a periodic bulk of methane.
Are both methods suitable for this kind of system?

The trend of the wannier total dipole and berry total dipole are almost the same, apart for a rescaling factor (total_wannier = 4.5 * total_berry + K), with K a constant.

Thank you very much,
and be patient if the question is a bit trivial,
Marco and Andrea  
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