[DFTB-Plus-User] How to effect a non-scc dftb calculation, it the current SK parameter compatible ?

[Peter Yen]

Dear Mr. Balint
Thank you for your information. I will consult further if i have any other
questions on the Rp part.




                                                          With Best Regards
  Peter



2017-03-24 11:38 GMT+08:00 Bálint Aradi <aradi at uni-bremen.de>:

> Dear Peter,
>
> > Thank you for your kind reply. You have mention that the repulsive
> > energy (RP) is fitted to bulk system of gold and since crystal gold
> > will not have charge transfer or nearly zero charge transfer, the RP
> > fitted will be similar to the non-scc case. However, in the case of
> > gold clusters, there are in fact non zero charge transfer among
> > atoms. And i believe the Rp in this case will be quite different to
> > the bulk case since  charge transfer now occurs in the former. In
> > these two extreme cases ( bulk gold and gold clusters Au_n, where n
> > is less than 10 ), do you think two separate RPs is necessary ?
> > Because the Rp in Au-Au.skf is actually fitted to system with nearly
> > zero charge transfer, yet in small clusters case, the charge transfer
> > can't be neglected. I was speculating maybe  the Rps will be quite
> > different in these two cases. Would you provide any comments or
> > advice ? Many thanks.
>
> According to DFTB theory, the repulsive potential is only a functional
> of the reference density, which is the superposition of the compressed
> neutral atom densities. So the difference, between a system with
> considerable charge transfer and a system with almost no charge transfer
> must be described by the scc-part of the Hamiltonian, not by the
> repulsive, as the reference density is similar in both cases. Therefore,
> when done with care, it is usually possible to create repulsive
> potentials, which are good compromises for both cases.
>
> Best regards,
>
> Bálint
>
> --
> Dr. Bálint Aradi
> Bremen Center for Computational Materials Science, University of Bremen
> http://www.bccms.uni-bremen.de/cms/people/b-aradi/
>
>
>
> _______________________________________________
> 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
>



-- 
Postdoctoral fellow, Physics department,
National Central University, Taiwan(R.O.C)
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://mailman.zfn.uni-bremen.de/pipermail/dftb-plus-user/attachments/20170324/044432ce/attachment.html>