[Pw_forum] Praseodymium Pseudopotential(s)

w2agz w2agz at pacbell.net
Wed Aug 25 23:31:14 CEST 2010

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
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