[CP2K-user] [CP2K:19511] Re: How to compute and output the dipole of the whole system during AIMD simulations?

[Alexandre Pinto]

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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