[DFTB-Plus-User] Fwd: SCC convergence problem for cluster calculation

[Anjali Singh]

Dear Aradi
                Thank you very much for your reply. In this case geometry
is unphysical , so ConvergentForcesOnly = No worked for my problem. Thanks
a lot.

On Wed, Oct 17, 2012 at 11:31 AM, Bálint Aradi <
balint.aradi at bccms.uni-bremen.de> wrote:

> Dear Anjali,
>
>   Apart of some special cases, DFTB+ shows usually a nice SCC
> convergence behaviour. Are you sure, that your input is physically
> meaningful? Especially, that atoms are not unphysically close to each
> other?
>
>  One thing I note in your input, that your Broyden-mixing parameter is
> extremely low. Usually, 0.1-0.2 is the right range. Also, you could as
> suggested by Rodrigo already, set SCCTolerance less tight as the default
> value (e.g. set it to 1e-4 instead of the default 1e-5).
>
>   Alternatively, if you geometry is rather unphysical, you could set
> ConvergentForcesOnly = No in the ConjugateGradient section. This would
> allow for relaxation along non-convergent forces as long as your system
> does not become more physical. Similarly, you could just set SCC=No for
> a while, relax the sytem, and restart then with SCC = Yes.
>
>  I hope, some of the ideas will help you.
>
>   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/
>
>
>
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>


-- 
With Thanks and Regards
Anjali Singh
Material Theory Group
Theoretical Science Unit
Jawaharlal Nehru Centre for Advanced Scientific Research
Jakkur,Bangalore 560 064
India
email id : anjalisinghromi at gmail.com
phone no:+91-89703-58107
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