[Pw_forum] TB09 metaGGA

[Paolo Giannozzi]

I don't remember if non-scf for metaGGA is implemented: if you
get funny results, it is likely that it isn't. Problem is, one 
often gets funny results also in scf calculations, in all but 
the simplest systems. Never found why.

Paolo

On Wed, 2014-10-29 at 19:50 +0100, Juanjo Meléndez wrote:
> Hi all
>  
> I am starting to work with metaGGA functionals in QE (v. 5.1 + libXc),
> following Èric Germaneau and colleagues’ work
> (http://dx.doi.org/10.1016/j.cpc.2013.02.020). I know that metaGGA is
> little tested, but I would be pleased if somebody could answer a
> couple of questions:
>  
> 1) Convergence is quite tricky. Up to know, I got some results in
> simple systems using a very small mixing_beta (within 0.01–0.05), not
> too many bands (just one or two conduction bands, never converged for
> more bands) and restarting from a previously fully converged
> calculation. I got results only for carbon, silicon and germanium,
> never got any convergence for any binary simple compound (like LiF).
> Does anyone have additional hints for metaGGA calculations to
> converge?
>  
> 2) In addition, I get something wrong with nscf calculations. After
> convergence of a scf run, I get a list of bands at each k-point, as
> usual –nothing strange here. Then I made a path of k-points to get the
> band structure and run a nscf calculation. This finishes fine as well,
> but the bands are not only different from those from the scf
> calculations, but also unrealistically high. I am attaching the input
> and output files for both the scf and nscf runs, as well as a couple
> of eigenval.xml files taken after nscf. Does anybody know how to
> manage this? Or could this be a bug in the code?
>  
> Thanks a lot in advance
>  
> Take care
>  
> Juanjo
>  
> Juan J. Meléndez 
> Associate Professor
> Department of Physics · University of Extremadura
> Avda. de Elvas, s/n 06006 Badajoz (Spain)
> Phone: +34 924 28 96 55
> Fax: +34 924 28 96 51
> Email: melendez at unex.es
> Web:
> http://materiales.unex.es/miembros/personal/jj-melendez/Index.html
>  
> ****************************
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>  
> ****************************
> 
> 
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-- 
 Paolo Giannozzi, Dept. Chemistry&Physics&Environment, 
 Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
 Phone +39-0432-558216, fax +39-0432-558222