[CP2K-user] [CP2K:19744] Content of *.voronoi file

[Fangyong Yan]

Dear Hana,

For the current, the time derivative of the dipole moment, for charged
species, if the charge does not change like classical force field, then the
current is invariant to the choice of reference coordinates.

However, if the charge (electron charge density)  varies, such as in the
DFT calculation, then for charged species, the current is no longer
invariant to the reference coordinate.

Best regards,

Fangyong

On Sat, Jan 13, 2024 at 5:50 PM Fangyong Yan <fangyongyan2023 at gmail.com>
wrote:

> So basically if you use electron density, you don’t have center for
> electrons; if you use wannier center, you have molecular orbital, and you
> define the center. But in practical, you can say all the centers are
> indistinguishable because electrons are indistinguishable.
>
>
> Fangyong
>
> On Sat, Jan 13, 2024 at 5:36 PM Fangyong Yan <fangyongyan2023 at gmail.com>
> wrote:
>
>> Dear Hana,
>>
>> I may misunderstand your question, but I think if you use Wannier
>> function, you have the Wannier center for electrons (molecular orbitals);
>> however, if you use voronoi method, you dont have the charge center for
>> electrons, the charge density for voronoi is the summation contribution
>> from all molecular orbitals (the square of molecular orbitals is the
>> probability density for electrons).
>>
>> Best regards,
>>
>> Fangyong
>>
>> On Sat, Jan 13, 2024 at 5:00 PM Fangyong Yan <fangyongyan2023 at gmail.com>
>> wrote:
>>
>>> Dear Hana,
>>>
>>> Dipole moment for  a neutral molecule or molecular system including
>>> ionic liquids with the total charge = 0, is invariant from your choice of
>>> coordinate systems (you shift your original coordinate center from (0,0,0)
>>> to (a,b,x)), the dipole moment does not change.
>>> However, this does not apply to charge species. So if you calculate the
>>> dipole moment of an Emim cation, it does not have strict physical meaning
>>> because once you change your center to a new center, the dipole moment
>>> changes. However, if you put a cation and an anion together, then the
>>> dipole moment is meaningful.
>>> On the other hand, the time derivative of dipole moment, is also
>>> invariant to the choice of coordinate system.
>>>
>>> Best regards,
>>>
>>> Fangyong
>>>
>>> On Thu, Jan 11, 2024 at 7:56 AM Hana <holiaei2 at illinois.edu> wrote:
>>>
>>>> Dear CP2K community,
>>>>
>>>> I have used the voronoi integration feature of CP2K to dump information
>>>> related to charge centers and dipole moments. In the *.voronoi file I
>>>> notice that there are "Position", "Charge", "ChargeCenter" and "Dipole"
>>>> columns. For a specific atom, I want to compare the "Dipole" value with the
>>>> "Charge" * ("Position"+"ChargeCenter") value. However, they turn out to be
>>>> quite different. Does anyone have a suggestion on this?
>>>>
>>>> Thanks!
>>>>
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>>>>
>>>

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