[DFTB-Plus-User] Electronic temperature

[Bálint Aradi]

Dear Reinaldo,

> Following your advice, I've compared the total energy and the Mermin
> free energy for those hard_to_converge cases I mentioned in my former
> mail. I've noted that the difference between them is a few tenths of eV
> for, say, 20-50 K. I guess this is a good result but now a new question
> arises: Can the difference between the total energy and the Mermin free
> energy be taken as a measure of the reliability of the results? In other
> words, can I state that the smaller the difference between the total
> energy and the Mermin free energy, the more reliable the result?
> 

I have difficulties to interpret the phrase "more reliable results". At
finite temperature you have non-integer occupancies. If you want to
simulate a system at exactly 0 K, and are switching on temperature only
in order to achieve convergence, that would indeed "falsify" your
results to some extent. The difference between the two energies would
then indicate you, how far you are from the case with electron
distribution at 0 K. But otherwise I do not think, you can get a
"reliability" information from that.

  Cheers,

   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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