Subject: Re: CCL:Pseudopotentials

From: "Artem R. Oganov" <[email-masked]>
Date: Fri, 12 Feb 1999 14:29:18 +0000

Dear all,

    I received one reply from Reinaldo Piz Diez. Thanks, Reinaldo.

>
>		A given PP gives place to pseudo valence wave functions (vwf) that must
>mimic the all-electron vwf outside a given radius. This radius is tipically
>chosen around the outermost maximum in the all-electron vwf. When that
>radius is chosen relatively small, it is said that the PP is hard because
>you need a great number of functions to describe the pseudo vwf. On the
>other hand, when the radius is larger, the PP is soft since a relatively
>modest number of functions is sufficient to describe the pseudo vwf.
>Moreover, in these cases the "norm-conservation" is impossed to the pseudo
>vwf.
>		In the ultrasoft PP, you basically retain all the advantages of the soft
>PP but now the norm-conservation is removed making the pseudo vwf smoother
>in the core region. 
>		You should have a look at "Planewaves, Pseudopotentials and the LAPW
>Method" by David Singh. You should find a lot of useful references there.   
>		Hope this helps a little.
>		Regards,
>
>						Reinaldo
>	
>
>