Dear Juanjo, From what I can remember: - the meta-GGA kinetic terms are not saved in order to restart a nscf, at least up to the 5.0 version, - the tools for building meta-GGA PPs are not available in QE. However, I'm not sure using meta-GGA pseudos will solve your problem. Meta-GGA are known to have numerical instabilities such as the ones you met, in particular when then electronic density drop to a very low level as probably in your ionic crystal LiF, on the contrary with Si and C that form covalent structures.
You can have a look to this paper you probably know: E.R. Johnson, JCP 131, 034111 2009 I don't believe a cure to you problem exists at the moment, except by changing the functional to a GGA one. Best regards, Yves . Le 31 oct. 2014 à 09:26, Juanjo Meléndez a écrit : > Hi Pascal > > Thanks for replying. I agree with you that building a PP consistent with the > metaGGA functional would solve most of the instability problems. But I do not > have *any* experience building PPs (which, by the way, seems to be not > trivial to me, even less trivial for metaGGA), so I followed > http://dx.doi.org/10.1016/j.cpc.2013.02.020 and tried the trick. I was just > wondering if any general strategy for convergence exists. > > Regarding point 2, I asked one of the authors of the aforementioned paper and > he declared not the have seen such a problem before, so I guess that the > kinetic terms are not responsible. I have overcome the problem by using a > dense kpoints path already in scf calculations and calculating the bands > without the standard intermediate nscf run, but it would be nice if the > developers could have a look and check. > > Again, thank you very much for your interest. > > 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: [email protected] > Web: http://materiales.unex.es/miembros/personal/jj-melendez/Index.html > > From: Pascal BOULET > Sent: Thursday, October 30, 2014 7:15 PM > To: PWSCF Forum > Subject: Re: [Pw_forum] TB09 metaGGA > > hello, > > I have never tried meta-GGA functionals with QE, so I am guessing. > > For point 1, one possible reason is the inadequacy between the pseudo > potential and the functional. I guess you have build a special > pseudopotential for this functional. > > Point 2: Could it be because the meta-GGA kinetic terms are not saved in the > checkpoint file and hence not readable when doing the nscf? > > > Pascal > > > "Juanjo Meléndez" <[email protected]> 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: [email protected] >> Web: http://materiales.unex.es/miembros/personal/jj-melendez/Index.html >> >> **************************** >> “All those who look stupid actually are, as also are half of those who do >> not look like” (F. de Quevedo) >> >> **************************** >> >> >> >> Este mensaje no contiene virus ni malware porque la protección de avast! >> Antivirus está activa. >> >> >> _______________________________________________ >> Pw_forum mailing list >> [email protected] >> http://pwscf.org/mailman/listinfo/pw_forum > > > > >----------------- > Pascal Boulet > Aix-Marseille University > MADIREL Laboratory > Avenue Normandie-Niemen > 13397 Marseille Cedex 20 > Email: [email protected] > Tel. +33 413 55 18 10 > Fax +33 413 55 18 50 > > > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum > > > > Este mensaje no contiene virus ni malware porque la protección de avast! > Antivirus está activa. > > > _______________________________________________ > Pw_forum mailing list > [email protected] > http://pwscf.org/mailman/listinfo/pw_forum
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