Hi, The USPP which includes sp semicore could lead you to that such ecut if it is not a very good PP. Ecutrho should be about 10-14*ecut and you should also make sure that the k-point sampling is good enough. Good luck.
On Wed, Sep 30, 2009 at 2:15 PM, Ary Junior <aryjunior at gmail.com> wrote: > Hi Lorenzo, I did exactly what you said and I got the same convergence > chart on both tests... I'm working with g-alumina and ultrasoft pp... My > first convergence test suggested an ecutwfc value between 50Ry-70Ry... Then > I used ecutrho = 280Ry for the second test... It means that I can use > ecutrho = 4*ecutwfc, right? > > []s > > Ary Junior > > > On Wed, Sep 30, 2009 at 1:00 PM, Lorenzo Paulatto <paulatto at sissa.it>wrote: > >> In data 30 settembre 2009 alle ore 17:48:41, udayagiri sai babu >> <udayagiri3 at gmail.com> ha scritto: >> >> > Dear all >> > I did convergence tests for chromium. The ecut value i obtained for >> > energy converged to 1mRyd is 60Ryd! which i believe is very high for an >> > Ultra Soft PP can somebody tell me if i am doing something wrong. Given >> > below are my >> > sample input file and ecut vs total energy. >> >> Dear Udayagiri, >> what about the cutoff for charge density? >> One good procedure to find a nicely converged cutoff is to increase >> ecutwfc until it converges than set ecutrho to 4*ecutwfc and reduce >> ecutwfc keeping ecutrho fixed. >> >> Maybe you can fix ecutrho to 240 and see how low you can go with ecutwfc >> >> best regards >> >> >> -- >> Lorenzo Paulatto >> SISSA & DEMOCRITOS (Trieste) >> phone: +39 040 3787 511 >> skype: paulatz >> www: http://people.sissa.it/~paulatto/<http://people.sissa.it/%7Epaulatto/> >> >> *** save italian brains *** >> http://saveitalianbrains.wordpress.com/ >> _______________________________________________ >> Pw_forum mailing list >> Pw_forum at pwscf.org >> http://www.democritos.it/mailman/listinfo/pw_forum >> > > > > -- > http://lattes.cnpq.br/8221674673413336 > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > > -- -------------------------------------------------- Duy Le PhD Student Department of Physics University of Central Florida. -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20090930/ccf4fc30/attachment-0001.htm