Dear Stefano, Since I have the same interest of generating a PP for an rare-earth element (Yb), if you don't mind, could you send me the input that you used to generate PP for Ce. I am trying to generate a PP for Yb, using QE, but I have failed so far. I would like to look at the input file generating Ce PP to have an idea, since they are of the same Lanthanide family.
Thank you very much, Trinh Vo CalTech/JPL On 8/26/10 6:11 PM, "w2agz" <w2agz at pacbell.net> wrote: > Hi Stefano(s), > > Thanks for your feedback. I wouldn't be surprised that praseodymium would > have similar issues as cerium. Ce is [Xe]4f 5d 6s2 and Pr [Xe]4f3 6s2, > and, as I mentioned below, Pr-1237 is the only lanthanide copper oxide > perovskite that doesn't superconduct. (The Ce copper oxides don't form in > the same perovskite structure). > In any event, your comment that correlations in these materials are very > cogent, and that employing a LDA+U framework is mandatory. > > You mentioned "...posting pseudos on the web"...is it possible for QE users > to submit PPs they've found handy to the QE Wiki? I constructed a PP > favoring the Cu 3d9 4s2 configuration which I found very useful for > calculating ground state antiferromagnetic properties of CuO, both as > tenorite and tetragonal rocksalt. I generated it using the QE PP code, and > could make it available (no guarantees, of course!). > > -Paul > > > > -------------------------------------------------- > From: "Stefano de Gironcoli" <degironc at sissa.it> > Sent: Thursday, August 26, 2010 12:21 AM > To: "PWSCF Forum" <pw_forum at pwscf.org> > Cc: "Stefano Fabris" <fabris at democritos.it> > Subject: Re: [Pw_forum] Praseodymium Pseudopotential(s) > >> Dear Paul, >> I have no experience with Praseodymium but have been involved in some >> calculations with Cerium that shares with it the mixed valence nature. >> Stefano Fabris (here in cc) generated a couple of pseudopotentials >> that were successfully used in a number of studies. He can send you >> more info... and possibly post the pseudos on the web... >> Beware however that in order to obtain even qualitatively sensible >> results with Ce (and I guess also with Pr) DFT+U or a similarly >> self-interaction corrected scheme is mandatory. >> best regards, >> Stefano de Gironcoli >> >> >> w2agz wrote: >>> Ciao Tutti (especially Paolo, Mateo etc.), >>> >>> >>> >>> OK, I've been away for a while, busy with energy issues and trying to >>> understand why Alex Mueller may have been on the right track wrt to >>> explaining why high temperature superconductivity manifests in the copper >>> oxide perovskites. PW_FORUM is not the right place to "advertize" one's >>> publications, but I owe much to the QE community and its creators and >>> contributors. Contact me if you're interested in further info. >>> >>> >>> >>> The reason for this posting is as follows: >>> >>> (1) I'd like to investigate via QE-DFT the "properties" of several Pr, >>> alkaline earth-oxide perovskites, and thus need to have an appropiate Pr >>> pseudopotential, one that would be compatible with the PP library of QE. >>> >>> (2) Browsing the QE, Vanderbilt, Opium, Haber and Martins sites >>> (US-PS, NC-PS), I could find "none" that were pregenerated. >>> >>> (3) Therefore, I may be "on my own," and would appreciate advice: >>> >>> a. Is the community aware of any suitable Pr PPs I could obtain and >>> use? >>> >>> b. If not, I'd appreciate advice on how to generate my own, using >>> either the "famous" ld1.x, or a suitable equivalent >>> >>> c. Does anyone know about or use the "Octopus" site >>> (http://www.tddft.org/programs/octopus) >>> >>> (4) Pr is a particular pernicious element ([Xe] 4f3-6s2) . Simply >>> put, it can be either 3+ or 4+.or somewhere in between - the 4f states >>> are known to hybidize extensively. Studies I did at IBM on the Pr-1237 >>> system indicated its ground quantum state may be in some sort of "heavy >>> fermion" configuration. Think about it. Why is not Pr-1237 >>> superconducting.or even metallic, even though its crystal structure is >>> nearly identical to Y-1237? That's the most unsolved mystery of 20th >>> century condensed matter physics.next to why the copper oxide perovskites >>> are superconducting at all. >>> >>> >>> >>> Finally, I remind all of the wisdom of David Vanderbilt's remark, >>> something to the effect, "Pseudopotential generation is a black art." >>> >>> >>> >>> Paolo, can you work your magic? >>> >>> >>> >>> Ciao, -Paul >>> >>> >>> ------------------------------------------------------------------------ >>> >>> _______________________________________________ >>> Pw_forum mailing list >>> Pw_forum at pwscf.org >>> http://www.democritos.it/mailman/listinfo/pw_forum >>> >> >> _______________________________________________ >> Pw_forum mailing list >> Pw_forum at pwscf.org >> http://www.democritos.it/mailman/listinfo/pw_forum >> > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum
