[DFTB-Plus-User] High repulsion between atoms - Increase in Temperature

[Bálint Aradi]

Dear Meral,

Your question is not basic at all.

When the pairwise repulsive potentials are fitted, usually only the 
equilibrium bond length +/- 10-30% are sampled. In order to extend the 
resulting repulsive potentials down to R=0, an exponential head part is 
fitted. Latter has no physical relevance, though, it is simply attached 
continuously to the rest. Therefore, its explicit form is rather 
arbitrary...

If you wish to make simulations at such a high energy scale, one would 
have to sample those short distances during the repulsive potential fit 
as well, and include them explicitly into the fit.

Best regards,

Bálint


On 24.05.23 20:21, Sharkass, Meral wrote:
> Hello all,
> 
> I am new to dftb+. I am trying to bombard a W-O system with H. Once I
> bombard the system with just 5eV of H, I am seeing a high increase in
> temperature (more than expected from bombarding). When I visualized
> the system, I can see that the H is very close to some W atoms
> causing high repulsion force .. My question is, "is there a command
> that prevents atoms to approach each other at close distances”?
> 
> Looking forward to hearing from you and I apologize if it is a basic
> question.
> 
> Best regards, Meral _______________________________________________ 
> DFTB-Plus-User mailing list DFTB-Plus-User at mailman.zfn.uni-bremen.de 
> https://mailman.zfn.uni-bremen.de/cgi-bin/mailman/listinfo/dftb-plus-user

--
> 
Dr. Bálint Aradi
Bremen Center for Computational Materials Science, University of Bremen
http://www.bccms.uni-bremen.de/cms/people/b-aradi/


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