Dear Lorenzo thanks for the answer. My problem is simple it is to find out the cohesive energy of Cr,V,Ti. I posted this question earlier also. I was told to try out with occupations=from_input instead of degauss value to get the accurate value of the ground state energy because i am getting an error of around 10% in Ec (i was wondering if that can be acceptable) meanwhile i came across the post which says to use ocuupations=fixed.
On Wed, Oct 7, 2009 at 1:09 PM, Lorenzo Paulatto <paulatto at sissa.it> wrote: > In data 07 ottobre 2009 alle ore 09:24:28, udayagiri sai babu > <udayagiri3 at gmail.com> ha scritto: > > > In the archive I have seen a discussion suggesting use of > > occupations=fixed to find out the ground state energy of isolated oxygen > > atom accurately. Can I use the same (occupations=fixed) for metal also. > > Because in the pw > > document it is told to use only for insulators. > > > Dear U, > for isolated atoms you can always use fixed occupations: as you use only > use the Gamma point, bands are actually flat. Nevertheless it may be > difficult to reach the ground state in some cases, I suggest using a small > smearing which should give exactly the same result but makes convergence > faster. > > I see you have already asked how to compute the ground state for a Ti atom > (e.g. > <http://www.democritos.it/pipermail/pw_forum/2009-September/014246.html>), > which actually is a metal... why don't you tell us your problem, instead > of your guess for a solution? > > 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 > -- U.Saibabu PhD student, Deformation mechanisms modeling group, Materials engineering department, IISc Bangalore, India. -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20091007/df679726/attachment.htm