[CP2K:1756] Re: Total dipole via LOCALIZATION - bug?

[Juerg Hutter]

Hi Fawzi

> The thing my code did and is not done now is simply to remove jumps by
> L/2*pi, and output also the finite derivative of the dipole, this
> could also be added to the present code as an option.
>
> If you use the total dipole of a periodic system setting the reference
> to COAC is not so useful, and does not allow you to remove the jumps
> easily.

Can you explain why the removal of jumps depends on the reference point?
If you use COAC there is only one non-zero term, meaning there is also
one term that can jump. For all other cases both contributions can
jump independently.

Juerg

>
> Fawzi
> On 3-feb-09, at 11:54, viki wrote:
>
>>
>> Please, this code was written originally by Fawzi (so I think) for an
>> article which we wrote jointly on IR spectra - the explicit purpose of
>> that PBC code was to avoid jumps in total dipole derivative due to
>> periodicity. I have an old version of QS with Fawzi's programming in
>> which this problem did not exist - but it does not include dispersion
>> which I now need. I would rather not install the code again unless
>> this particular problem was addressed - is there any way to ask the
>> person who fixed the bug, if he addressed this particular problem?
>> Thanks much! Victoria
>>
>> On Jan 31, 7:09 pm, Juerg Hutter <hut... at pci.uzh.ch> wrote:
>>> Hi
>>>
>>> there was a bug fix regarding the PBC dipole recently:
>>>
>>> Fri Jan 9 18:32:09 2009 UTC (3 weeks ago) by vondele
>>>
>>> Are you running an updated version?
>>>
>>> The Berry phase dipole is only defined within modulo L/2Pi.
>>> Jumps of multiples of this value are expected to appear.
>>>
>>> You can also calculate the total dipole moments without
>>> localization with
>>>
>>>   CP2K_INPUT / FORCE_EVAL / DFT / PRINT / MOMENTS
>>>
>>> There you can set
>>>   REFERENCE COAC
>>>
>>> this will minimize the number of jumps by setting the
>>> reference point to the center of atomic charges, i.e.
>>> the contribution to the dipole from the nuclear charges is
>>> zero. The same applies to the localization based method.
>>>
>>> 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
>>> ----------------------------------------------------------
>>>
>>> On Sat, 31 Jan 2009, v.... at fh.huji.ac.il wrote:
>>>
>>>> Hello,
>>>> I am running
>>>>       &LOCALIZATION
>>>>          &TOTAL_DIPOLE
>>>>            &EACH 1
>>>>                &END
>>>>          &END TOTAL_DIPOLE
>>>>       &END LOCALIZATION
>>>> with the objective to calculate system dipole derivative as a
>>>> function
>>>> of time (I need the IR spectrum). The system is periodic (one unit
>>>> cell of clathrate hydrate, which includes water, H2S and ethylene
>>>> oxide), DZVP-BLYP with Grimme van der Waals correction.
>>>
>>>> So here is a problem - now and then the dipole derivative jumps to
>>>> some preposterously huge value (positive or negative). These are
>>>> isolated points. To me it seems as if Berry phase formula which is
>>>> supposed to correct for periodicity does not work, although it is
>>>> supposed to be a default. Any advice? Thanks, Victoria Buch
>>>
>>>> ----------------------------------------------------------------
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>>
>
> >
>