Thank you a lot Mr Lorenzo for your suggestions. I will try them and thank you again for your help.
Regards, On Wed, Dec 16, 2009 at 11:22 AM, Lorenzo Paulatto <paulatto at sissa.it>wrote: > Replying to message "[Pw_forum] graphene on BN calculation" from mohamed > sabri majdoub (16/12/09): > > > I am not sure that I am doing it the right way. I am using 40 processors > > and I the calculations look very slow to me. > > Well, it's a big system. You can speed it up by using tqr=.true. > (real-space augmentation charge). There is also an experimental real-space > algorithm, but I don't know how reliable it is at the moment (you can > contact baris _at_ sissa.it for additional info). > > > tstress = .t. > > there is no need to print the stress, and it takes time to compute (not > much) > > > diagonalization = 'cg' > > For better performance you should use the default (david). If you have > some problem with it, you should ask for help on the forum before falling > back to cg, which is non much more robust and quite a bit slower. Also, > diagonalization errors are most of the time input errors/bad atomic > positions. > > > > K_POINTS automatic > > 30 30 1 1 1 0 > > this is a huge number of k-points for such a cell, are you sure you need > all of them? Remember that every time you increase the cell size by N you > can reduce the number of k-points by the same factor. (e.g. a 2x2x2 > super-cell only need on eighth of the k-points of the original cell). > Computation time scales linearly with the number of points, e.g. "10 10 1 > 1 1 0" will be about 9 times faster. > > 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 > -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20091216/d709db9e/attachment-0001.htm
