[CP2K:4737] difference between wannier total dipole and berry total dipole

[Wagner Homsi Brandeburgo]

Thank you for your reply,

so if the reference change this difference between subsequent references
should be added to the delta dipole, since the way it's calculated now the
delta dipole is just the difference between the total dipole of a given
time step and the previous one, right?

Cheers,
Wagner.


On Fri, Oct 25, 2013 at 4:37 PM, <hut... at pci.uzh.ch> wrote:

> Yes, the reference (COAC) will change during a MD. Although
> not 'jump' with the proton, as the oxygens have a much higher
> weight.
> Be careful when calculating charged systems! Now the dipole depends
> on the choice of the reference point. If you change the reference point
> during a MD also the dipole differences will change!
>
> regards
>
> Juerg
>
> --------------------------------------------------------------
> 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: Wagner Homsi Brandeburgo
> Sent by: cp... at googlegroups.com
> Date: 10/25/2013 03:46PM
> Subject: Re: [CP2K:4736] difference between wannier total dipole and berry
> total dipole
>
> 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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