[Wien] Energy scale in XSPEC or ELNES

Shu Miao shu at caltech.edu
Fri Sep 15 22:52:50 CEST 2006


Dear Wien2k users
As we know, the energy scale Ea in XAS or EELS is the difference between
the final state Efand the initial state Ei, i.e., Ea=Ef-Ei. This is an
absolute value regardless where is the zero energy point.
In my calculation, the core state of Fe 2p is -50.3Ry. The experimental
energy loss of L3 peak (2p -> 3d) is about 707eV. So I will expect the
calcualted peak (the position of the unoccupied d states) will be around
20eV above the Fermi level so that the difference between 2p and 3d is
close to 707eV. However, all XSPEC, ELNES and DOS tasks give a peak just
above the 0eV (Fermi level), though the shape looks right. In my case,
both Fe and O have this problem.
Does anyone have experience of this and know what causes the problem?
Is this caused by an inaccurate calcualted core energy? Can the inaccuracy
be up to 2Ry in my case? The scf converges well.

Thanks

Shu Miao


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