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

[Anjali Singh]

When i am putting CalculateForces = Yes in input file, it is giving error.
How to get forces on each atoms?

On Wed, Oct 17, 2012 at 12:56 PM, Ben Hourahine <
benjamin.hourahine at strath.ac.uk> wrote:

> Hello Anjali,
>
> On extra things to try, is to increase the electron temperature.
> 10 Kelvin is quite small, several hundred is more common (but
> the choice depends on your band structure).
>
> Regards
>
> Ben
>
>
> On 17/10/12 07:01, Bálint Aradi 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. B. Hourahine, SUPA, Department of Physics,
>    University of Strathclyde, John Anderson Building,
>           107 Rottenrow, Glasgow G4 0NG, UK.
>     +44 141 548 2325, benjamin.hourahine at strath.ac.**uk<benjamin.hourahine at strath.ac.uk>
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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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