Dear Jia, I checked those pp and there are not recommended cutoffs. When I use occupation=fixed, the results are similar as those from occupation=smearing (reach minimum at 80 Ry) . And the scf doesn't converge when ecutwfc=60 Ry.
Ecutwfc energy total force 50 -1129.7209 0.7937 60 no convergence 70 -1136.6081 0.7066 80 -1137.3776 0.7059 90 -1137.3342 0.6997 100 -1136.9523 0.7056 On Mon, Sep 10, 2012 at 5:17 PM, Jia Chen <jiachenchem at gmail.com> wrote: > Dear Peng, > > For AFM case, you can set tot_magentization = 0, for FM case, you need > to know tot_magnetization from experiments or previous calculations. > Or you can use the int(absolute magnetization) from you AFM > calculations. > > Trying to converge total energy with respect to wave function cutoff > is usually not a good idea. If you just want to choose a good cutoff > energy for calculations, first thing you can do is to look into those > pseudopotentials you are using. If you can find recommended cutoffs, > you probably can just use the highest cutoffs in your system. > > Bests > Jia > > On Mon, Sep 10, 2012 at 5:02 PM, Peng Chen <pchen at ion.chem.utk.edu> wrote: > > Dear Dr. Giannozzi, > > > > Thanks for your reply. I use smearing for computing the band structure in > > afm and fm states. It looks there is still a lot to learn. If I use > > occupation=fixed to calculate afm/fm states, shall I just set > > tot_magnetization=0 or 1? > > > > If I didn't set ecutrho, the default value of ecutrho is 4*ecutwfc. So > the > > results are the same as the following, and the energy doesn't decrease > > monotonically. I tried to decrease degauss to 0.005 Ry, I got the similar > > results. What I can do to make the energy converge? > > > > ecutrho=4*ecutwfc > > ecutwfc energy total force > > 30 -1086.672528 1.335253 > > 40 -1119.972723 0.690327 > > 50 -1129.973333 0.690484 > > 60 -1134.622157 0.640747 > > 70 -1136.892534 0.617201 > > 80 -1137.666471 0.616635 > > 90 -1137.620919 0.610216 > > 100 -1137.238099 0.615361 > > 110 -1136.89911 0.62063 > > 120 -1136.866006 0.622763 > > > > On Mon, Sep 10, 2012 at 3:45 PM, Paolo Giannozzi <giannozz at democritos.it > > > > wrote: > >> > >> > >> On Sep 10, 2012, at 16:35 , Peng Chen wrote: > >> > >> > I tried to calculate an insulator Ni3V2O3 using pbe norm conserving > >> > pp from pslibrary. But the energy related with ecutwfc is not > >> > converged. It reaches minimum at ecutwfc=80 Ry. But when I fix > >> > ecutrho=320 Ry and increase ecutwfc, it starts to decrease > >> > monotonically. I am not sure if the system reaches the convergence > >> > at ecutwfc=80 Ry. > >> > (smearing=mv, Degauss=0.01 Ry and kpoints = 4 4 3) > >> > >> if it is an insulator, why are you using smearing? Apart from this: > >> with norm-conserving PP, ecutwfc is the only parameter defining > >> the basis set. You should not set ecutrho. > >> > >> P. > >> --- > >> Paolo Giannozzi, Dept of Chemistry&Physics&Environment, > >> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy > >> Phone +39-0432-558216, fax +39-0432-558222 > >> > >> > >> > >> > >> _______________________________________________ > >> Pw_forum mailing list > >> Pw_forum at pwscf.org > >> http://www.democritos.it/mailman/listinfo/pw_forum > > > > > > > > > > -- > > Best Regards. > > Peng > > > > _______________________________________________ > > Pw_forum mailing list > > Pw_forum at pwscf.org > > http://www.democritos.it/mailman/listinfo/pw_forum > > > > > > -- > Jia Chen > webpage: www.princeton.edu/~jiachen > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > -- Best Regards. Peng -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20120910/a00e8a29/attachment.htm
