[Pw_forum] On Lowdin charges (again)

[Paolo Giannozzi]

On Fri, 2013-03-15 at 13:54 +0100, glevita at units.it wrote:

> The p orbitals of the Mo atom are filled by 7 electrons, which is odd as well.

if you have semicore states, it is possible: 6 p electrons in the
semicore states, one in the valence state.

> Do you think that for covalent compounds such as MoS2 a reliable  
> Lowdin analysis is rather unfeasible or - as I think - I am missing  
> some point in evaluating its outcome?

I am not a big fan of Mulliken/Lowdin/Hirschfeld/whoever charges, 
but it seems to me very unlikely that they are so utterly useless,
even in a material like MoS2. Have you tried to experiment with 
simpler materials and verify that you get what you expect (and 
that what you expect is really what you should expect)?

BTW: remember that the projection is done on atomic functions
that are present in the pseudopotential file. No atomic functions
(or not all of them), no projection (or bad projections, missing 
charge, etc.)

Paolo
-- 
Paolo Giannozzi, Dept. Chemistry&Physics&Environment, 
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222