[Wien] A question

[Stefaan Cottenier]

> I'm puzzling about a question, when we have finished a scf, how to decide the valence of an atom.
>
Very difficult, valencies are formal designations and not reflected in a
straightforward way in the charge on an atom. What you call "+2" does
not have 1 full electron more than what you call "+3" (convince yourself
by calculating the total charge on Na and Cl in NaCl -- very quick job
with wien2k. Do you find +1 and -1?). Also the role of the interstitial
enters: what do you call the boundary of an atom? The muffin tin sphere?
Bader volume? ... Summarized: no simple answer is possible. You can
probably assign valencies, but what to look for will depend on your case.

> In the process of finding the answer, I'm in another puzzle, In case.scf there is 
>CHA0XX:   and  CTO0XX: 
>What is the difference between them .
>
:CHA : number of valence electrons in the muffin tin sphere. Yet
unmixed. One value for up, one value for down.
:CTO : total number of electrons (core + valence) in the muffin tin
sphere. Already summed for up and down. Mixed density.

Stefaan


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