[Pw_forum] A question about generating NC-pseudopotential for Fe

[Paolo Giannozzi]

On Tuesday 10 May 2005 17:21, Xinjie Wang wrote:

> My purpose is to generate a NC-PP for Fe as good as possible regardless
> of how hard it is.
> In this case of pseudotype=2, rel=2, can I use more than one projector
> (not state) per angular momentum to get good results?

My understanding is that you can use the semicore (3s) state and another 
(unbound) state at an energy not too close and not too far from the energy
of the former. Presently you cannot use both the semicore and the valence 
(4s) state: they have to be orthogonal to each other, i.e. the valence state
has to have a node, and this is not presently implemented.

I have always used only the semicore states in such cases, but the
resulting PPs are not exceedingly accurate: they work very well in
the energy region around semicore states, less so around valence
states. Of course it would be preferrable to use more than one 
projector (i.e. state, bound or unbound) per angular momentum

Paolo