Dear Yuva, I believe you should test the convergence of the total energy as those parameters vary. Usually, ecutrho should be between 8 to 14 times the value of ecutwfc, depending on the material. For example, you could run a scf calculation using, say, ecutwfc=30, ecutrho=300, then again with ecutwfc=40, ecutrho=400 and so on, and check the total energy convergence. Then given a value of ecutwfc, you can vary ecutrho to see which values lead to convergence. This is needed in order to find a setup that mixes precision with computational cost well. If, on the other hand, you don't care about computational cost, then you could use, say, ecutwfc=200 and ecutrho=2800 and I'm pretty sure you'll have a well converged calculation, altough it'd take a very long time to evaluate it (or not, if you can use a very powerful computer).
Best, Giovani M. Faccin UFMS/Unicamp - Brazil 2011/6/8 yuva rani <syuva2987 at gmail.com> > On 6/8/11, yuva rani <syuva2987 at gmail.com> wrote: > > I am trying to relax a gold surface consisting of 112 atoms. I > encountered > > a > > error in the output file as negative rho (up, down). I need the guidence > of > > the ecutwfc for gold and how to set this value. > > *Thank you and Regards, > > ** > > ** S.Yuva > > ** Physics Department > > ** Bharathiar University.* > > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > -- Giovani -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20110608/0ec9a511/attachment.htm
