Dear Mohnish, thanks for you answer. I will follow your suggestion and try also HSE, with a coarser k-point mesh, (indeed with PBE0 the computation time is quiet large), and I did not know about projwfc.x. I have a further question concerning the DOS. If I wish to know about the DOS of my system, which uses the hybrid functional implementation, am I able to use the projwfc.x? Is'n it a postprocessing tool? Thanks, regards, Valentina
Il 04/09/2013 11:18 AM, mohnish pandey ha scritto: > Hi, > > As far as I can understand there is no rule. It depends how fine you > want to represent your Fock operator. Normally calculations of the > Fock exchange in expensive, so its not affordable to do very fine grid > calculations So I suggest you start with low nqx(1, 2, 3) and > increase it systematically. Increasing it will give you better > results( I mean converged results, not necessarily close to experiments). > > Just an advice, PBE0 needs much more high density k-point mesh for the > convergence of Fock exchange since it's a long range interaction. So > you have to do calculations with high density of k-points. But if you > use HSE instead of PBE0 you get away with coarser k-point mesh since > it involves screened exchange interaction which converges much faster > than bare Coulomb exchange as in PBE0. Regarding to the DOS plot you > will find a nice tutorial on Heither's website, I am pasting the link > http://www.stanford.edu/~hkulik/www/Tutorials/Entries/2012/1/24_Population_analysis_and_PDOS.html > > <http://www.stanford.edu/%7Ehkulik/www/Tutorials/Entries/2012/1/24_Population_analysis_and_PDOS.html> > > > On Tue, Apr 9, 2013 at 10:05 AM, "Valentina Dellac? C.R.F. S.C.p.A." > <valentina.dellaca at tirocinanti.crf.it > <mailto:valentina.dellaca at tirocinanti.crf.it>> wrote: > > Hi, > I am a Quantum Espresso beginner user, and I am simulating the > Ta2O5 structure, with the employment of the hybrid functional > PBE0. I have some questions : > > - if I choose a k-point grid not in automatic, how should I pick > the nqx1,2,3? Is there a rule? > - when one wishes to have informations (ex. plot) about the > density of states from the scf run, how should I proceed? > > Thank you, > regards > Valentina >> >> -- > > > -- > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org <mailto:Pw_forum at pwscf.org> > http://pwscf.org/mailman/listinfo/pw_forum > > > > > -- > Regards, > MOHNISH, > ----------------------------------------------------------------- > Mohnish Pandey, > PhD Student, > Center for Atomic Scale Materials Design, > Department of Physics, > Technical University of Denmark > ----------------------------------------------------------------- -- -------------- next part -------------- An HTML attachment was scrubbed... URL: http://pwscf.org/pipermail/pw_forum/attachments/20130409/28123979/attachment.html -------------- next part -------------- A non-text attachment was scrubbed... Name: firma 2013.jpg Type: image/jpeg Size: 19579 bytes Desc: not available Url : http://pwscf.org/pipermail/pw_forum/attachments/20130409/28123979/attachment.jpg
