[Pw_forum] Does anyone have RRKJ uspp for Cr?

Nicola Marzari marzari at MIT.EDU
Tue Mar 27 20:19:19 CEST 2007

Chao Cao wrote:
> Thanks for both reply from Nicola and Degironc. However, I am not quite 
> confident in mixing Vanderbilt pp with RRKJ pp (is it justifiable?). I'm 
> going to try the rho0 thing, and if it doesn't work out I'll probably 
> just use Vanderbilt pp instead. Thanks again for both suggestions.
> Best,
> Chao Cao

Hi - there are absolutely no problems and no side effects in
mixing "Vanderbilt" ultrasoft PPs and "RRKJ" ultrasoft ones (RRKJ in
the pwscf sense, i.e. ultrasoft psp generated not from the real
atom, but from a RRKJ pseudoatom). It would also be fine to mix 
ultrasoft with norm-conserving pseudopotentials (e.g.
Troullier-Martins, RRKJ, Von-Barth-Car, Bachelet-Hamann-Schluter...), 
and even with plain local potentials (not that many that are any good,
a part from H...).

The code complains only if different exchange-correlation potentials
have been used in the generation of the atomic pseudopotentials, since 
then it wouldn't know wich xc to use for the calculation, and because
you shouldn't mix-n-match xc.


Prof Nicola Marzari   Department of Materials Science and Engineering
13-5066   MIT   77 Massachusetts Avenue   Cambridge MA 02139-4307 USA
tel 617.4522758 fax 2586534 marzari at mit.edu http://quasiamore.mit.edu

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