that was also done. JB Am Mon, 7 May 2012 09:41:35 -0400 schrieb Iyad AL-QASIR <iyad.ne at gmail.com>:
> Hello, > Try first to relax the atomic positions, then relax the structure. > > Thanks > > > On Mon, May 7, 2012 at 9:22 AM, J?rg Buchwald > <joerg.buchwald at iom-leipzig.de > > wrote: > > > Hi, > > i tested a relaxed sapphire structure using a 10x10x10 k point set > > with a cutoff energy up to 250 Ry. Even at this Energy, a change of > > +/- 5 Ry in the cutoff lead to stresses of the order of 1 kbar. > > I used for Al and O pbe-n-van US pseudo potentials from the pseudo > > folder of quantum espresso. But also pbe-sp-van for Al and rrkjus > > for oxygen led to the same problem. > > I don't have a clue how high the cutoff must be, but 250 Ry seems > > to be far too high. Is that a problem of the pseudopotentials or > > does it have something to do with physical structure of sapphire? > > Thx for any hints, > > J?rg Buchwald > > > > -- > > Leibniz-Institut fuer Oberflaechenmodifizierung e.V. > > > > Permoserstrasse 15 > > 04318 Leipzig > > GERMANY > > > > Phone: +49 341 / 235-3367 > > Web: http://www.uni-leipzig.de/~agmayr > > > > _______________________________________________ > > Pw_forum mailing list > > Pw_forum at pwscf.org > > http://www.democritos.it/mailman/listinfo/pw_forum > > > > > -- Leibniz-Institut fuer Oberflaechenmodifizierung e.V. Permoserstrasse 15 04318 Leipzig GERMANY Phone: +49 341 / 235-3367 Web: http://www.uni-leipzig.de/~agmayr
