[Wien] Ambiguity in instructions for XPS/XAS/TELNES

[Peter Blaha]

I do not have real experience with this and I don't think there are 
"global" rules, but one has to consider the specific case.

I guess in most cases it does not matter which spin you select for the 
core hole. The important thing is the coulomb potential, which is 
modified due to a missing electron. The exchange effect should be small.

I could imagine (without real experience) that this could be important 
for more localized cases like in 3d or in particular 4f elements, 
because the 4f valence electrons are spatially in a similar region as a 
higher core electron and thus direct exchange effects can happen.

In any case, typically XAS of localized 3d or 4f electron systems is not 
well described by the simple core-hole approach, since multiplet effects 
dominate the L2,3 or M4,5 spectra.

PS: Did you really see a spin change depending on a up/dn or 
"non-magnetic" hole ?

Am 15.02.2017 um 17:41 schrieb Laurence Marks:
> Also...there might be a deeper problem since if one uses an "up" core
> hole, unless FSM is used the final state can have a spin change.
>
> On Tue, Feb 14, 2017 at 4:24 PM, Laurence Marks
> <L-marks at northwestern.edu <mailto:L-marks at northwestern.edu>> wrote:
>
>     I think there is a slightly ambiguity for spin-polarized cases in
>     the UG. I don't see mention that one has to carefully setup
>     case.incup/case.incdn for the core hole (or fractional hole). From
>     what I can see it does not seem like this is an issue in the later
>     calculations, but I think it is easy for someone to inadvertantly
>     calculate a spin-unresolved for for a spin case.
>
>     N.B., for my own sanity, it would be nice if someone could confirm
>     that xtelnes/xspec don't really care about the occupancies in
>     case.inc, just an adequate list of states.
>
>     --
>     Professor Laurence Marks
>     "Research is to see what everybody else has seen, and to think what
>     nobody else has thought", Albert Szent-Gyorgi
>     www.numis.northwestern.edu
>     <http://www.numis.northwestern.edu> ; Corrosion in 4D:
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>     Partner of the CFW 100% program for gender
>     equity, www.cfw.org/100-percent <http://www.cfw.org/100-percent>
>     Co-Editor, Acta Cryst A
>
>
>
>
> --
> Professor Laurence Marks
> "Research is to see what everybody else has seen, and to think what
> nobody else has thought", Albert Szent-Gyorgi
> www.numis.northwestern.edu
> <http://www.numis.northwestern.edu> ; Corrosion in 4D:
> MURI4D.numis.northwestern.edu <http://MURI4D.numis.northwestern.edu>
> Partner of the CFW 100% program for gender
> equity, www.cfw.org/100-percent <http://www.cfw.org/100-percent>
> Co-Editor, Acta Cryst A
>
>
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
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