[CP2K-user] [CP2K:19514] Re: How to compute and output the dipole of the whole system during AIMD simulations?

[Matt Watkins]

I am not 100% sure. Relevant seems to be:

https://manual.cp2k.org/trunk/CP2K_INPUT/FORCE_EVAL/QMMM/PRINT/DIPOLE.html

"Controls the printing of the DIPOLE in a QM/MM calculations. It requires 
that the DIPOLE calculations is requested both for the QS and for the MM 
part."

but do sanity check your results / consider periodic boundary conditions 
etc.
Matt

On Wednesday, 15 November 2023 at 18:55:54 UTC Alexandre Pinto wrote:

> Dear Matt,
>
> Do you know if the moments keyword gives the dipole moment of the whole 
> system within the QM/MM implementation, or just the QM layer?
>
> Best regards,
> Alexandre 
>
> A quarta-feira, 4 de outubro de 2023 à(s) 06:47:36 UTC+1, Matt Watkins 
> escreveu:
>
>> The moments keyword gives the dipole moment of the whole system (which 
>> you seem to ask for). If your system if periodic you need to allow for that 
>> with the periodic keyword - dipole moments in a periodic system are only 
>> defined up to a point - consider drawing a box with two charges in it then 
>> shifting the box boundaries. There are many papers on this in the 
>> literature.
>>
>> The localise keyword converts the density into a Wannier representation 
>> centred on atoms from the original distributed density. These wannier 
>> centres can then be used to recalculate the dipole of the whole system or 
>> by grouping the wannier centres that correspond to molecules (as defined in 
>> a similar way to a forcefield calculation) molecular dipoles can be 
>> calculated. See PL Silvestrelli, M Parrinello - Physical Review Letters, 
>> 1999 - APS for instance.
>>
>> Matt
>>  
>>
>> On Wednesday, 27 September 2023 at 14:29:41 UTC+1 liu dongfei wrote:
>>
>>> Recently, I have been trying to find commands in the reference manual 
>>> and cp2k group for calculating dipole of the simulation system.
>>> I find one previous related message posted two years ago.
>>> https://groups.google.com/g/cp2k/c/KPmGDOqhwMM/m/QdTYMNZhAgAJ
>>> In that post, Mr. Chen mentioned three commands for calculating dipole 
>>> in cp2k reference manual. They are as follows:
>>>
>>>    1. Total dipole: 
>>>    https://manual.cp2k.org/cp2k-8_1-branch/CP2K_INPUT/FORCE_EVAL/DFT/LOCALIZE/PRINT/TOTAL_DIPOLE.html
>>>    2. Molecular dipole: 
>>>    https://manual.cp2k.org/cp2k-8_1-branch/CP2K_INPUT/FORCE_EVAL/DFT/LOCALIZE/PRINT/MOLECULAR_DIPOLES.html
>>>    3. moments: 
>>>    https://manual.cp2k.org/cp2k-8_1-branch/CP2K_INPUT/FORCE_EVAL/DFT/PRINT/MOMENTS.html
>>>    
>>> Mr. Chen said there exist differences between the results of Total 
>>> dipole and Molecular dipole. And the way of calculating Molecular dipole is 
>>> also unknown. 
>>>
>>> Mr. Chen's questions are also something that I want to know very much. 
>>> Looking forward to any guidance and help! 
>>>
>>> Regards,
>>> Dongfei
>>>
>>

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