Lorenzo: your (ir-)rationale may be more or less justified for separable potentials, but it is certainly wrong for good ol' semilocal ones. SB
On Jan 24, 2010, at 9:05 PM, Lorenzo Paulatto wrote: > I'm reposting here a message that I mistakenly sent privately to Brad: > > have a look at the total-energy components: if the one-electron > contributions increases at the expenses of the other terms (mostly > the hartree term) than you have found a ghost in the pseudopotential. > As far as I know, all non-local separable pseudopotentials have ghost > states for large enough values of the curoff. > > I'm not really sure my impression is correct, but I've always had > problems with large enough cutoffs with any pseudopotential I have > tried. My rationale is more or less on this line: the pseudopotential > only have Fourier components up to a certain threshold; plane waves > over that threshold do not feel any direct effect from the ions. As a > consequence this very high frequency plane waves gain nothing by > forming a charge density close to the ions, instead they can just > spread around to minimize the Hartree energy (which decreases) at the > expenses of kinetic energy (which increases). > > cheers > > > -- > Lorenzo Paulatto > SISSA & DEMOCRITOS (Trieste) > phone: +39 040 3787 511 > skype: paulatz > www: http://people.sissa.it/~paulatto/ > > *** save italian brains *** > http://saveitalianbrains.wordpress.com/ > > > ---------------------------------------------------------------- > SISSA Webmail https://webmail.sissa.it/ > Powered by Horde http://www.horde.org/ > > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum --- Stefano Baroni - SISSA & DEMOCRITOS National Simulation Center - Trieste http://stefano.baroni.me [+39] 040 3787 406 (tel) -528 (fax) / stefanobaroni (skype) La morale est une logique de l'action comme la logique est une morale de la pens?e - Jean Piaget Please, if possible, don't send me MS Word or PowerPoint attachments Why? See: http://www.gnu.org/philosophy/no-word-attachments.html -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20100124/d9e92b42/attachment-0001.htm
