[Wien] Normalization of the XAS spectra

[Peter Blaha]

The units of the momentum matrix elements were discussed in the mailing list
just a few days before and they should be "correct" (except see below).

For XAS you are probably using   xspec (or telnes)

In this case, in these programs the dipole matrix elements between
core and valence are calculated within the atomic sphere only,
which is perfectly alright if the core function is really zero
outside the sphere (check your core leakage), but since something is always
leaking out .....

When you say the spectra differ on the 10^-4 level:
What is the integral ? It seems pretty much the same for me.
I wonder how you do the integration (E-grid, method, ...)
and if this is even stable at 10-4

And I'm not surprised that a matrixelement (which determines the
intensity) changes if you substitute something ....


Am 04.03.2011 14:01, schrieb Lily Anh:
> Dear all,
>
> I asked the same question before which remained unsolved so far. Does anybody know the normalization scheme of the X-ray absorption spectra?
>
> I carried out XAS for very similar structures (same lattice constant, same atomic positions, only substitute several atoms) with same input parameters. I would like to check the
> spectral changes (like peak intensity) due to this substitution. However, I found the integration values of the spectra differ a little (in the 10-4 level) and hence the
> comparison of the peak intensity is unreasonable. Or should we say 10-4 is so small that we could ignore.
>
> Many Thanks!
>
> Lily
> PhD candidate
> Nanyang Technological Univerisity
> Singapore
>
>
>
>
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                                       P.Blaha
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Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
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