[CP2K:4735] difference between wannier total dipole and berry total dipole

[Wagner Homsi Brandeburgo]

Hi, I have another question on the same topic,

in the case of using REFERENCE COAC (center of atomic charges) for
calculating the total dipole of a protonated water system (bulk water +
hydronium),
if I understood it correctly the reference would be at the sum of the
nuclear charges,
I was wondering if the reference would then jump together with the proton
as it hops from one water molecule to the next.

Cheers,
Wagner.


On Fri, Oct 25, 2013 at 2:56 PM, <hut... at pci.uzh.ch> wrote:

> 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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