Force on Nuclei

Matt W MattWa... at gmail.com
Wed Oct 30 18:36:51 UTC 2013


Hi,

you wrote:

"I am interested for finding the forces working separately on nuclei and 
electrons (not every electrons). I have tried to print all the contribution 
but i have found only complete force on atom rather than individual 
contribution."

I think you need to make it clearer what type of analysis you are 
attempting. Within the Born-Oppenheimer approximation there is a force to 
move a nuclear center a certain distance. Whether it makes any sense to 
decompose it as you seem to be trying isn't clear to me.

For an isolated molecule you could work out the forces on the nuclei from 
the other nuclei using point charges. But in DFT there are no real atoms 
electronically, so this sort of partitioning is non trivial, even if you 
can find a way to justify it theoretically. In a periodic system things get 
even more difficult. CP2K combines the charges of electrons and nuclei to 
work out electrostatic interactions, and there would be no way to separate 
them, I think.

Long answer boils down to, I don't know how to do this, or if it is 
physically meaningful.

Matt

p.s. Best to keep everything on the list, then there is more chance of 
someone smart giving suggestions.

On Monday, 14 October 2013 18:24:49 UTC+1, Pankaj Mishra wrote:
>
> Dear All,
>
> I am doing some DFT calculation on water molecule with EF. I am interested 
> to know about the forces on nuclei and electrons. Is there some way in CP2K 
> by which i can get all forces working on nucleus and electrons?
> Looking forward to your response
>
> Thank you so much
>
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