[Wien] k-selectivity for RXES simulation ?

[Peter Blaha]

Unfortunately such tools are not yet present in an automatic way (in 
standard WIEN2k). So far I was always manually inspecting the 
bandstructure and than using "hand waving" arguments why there should be 
a shift in the spectra depending on excitation energies.

However, I'm interested in this topic and will come back to you.

Cormac McGuinness schrieb:
> Dear Wien2k users
> 
> I would be interested in using Wien2k to simulate resonant x-ray emission
> spectroscopy of a number of metal oxides. Specifically at the oxygen edge as
> the O 1s soft x-ray emission spectrum gives the O 2p partial density of states.
> 
> Experimentally we typically record spectra with polarised incoming light aligned
> along a specific crystal axis (O K-edge XAS), and the emission (O K-edge XES)
> recorded propagating to the detector along another arbitrary axis, usually at
> right angles. We can thus record soft x-ray emission spectra projected along
> specific crystal axes (or pairs of axes).
> 
> Now, if we are near threshold then it is not uncommon that for lone conduction
> bands that disperse slowly in a given direction from their minima as seen in
> our spaghetti plot, we end up selecting (in the x-ray emission) ever increasing
> sets of k-points that correspond to the k-points selected in the conduction band
> states due to the excitation energy chosen.
> This "k-selection" arises as the photon momentum is small, and thus the emission
> occurs in a vertical line conserving k.
> e.g. if the excitation is at the threshold for absorption and thus at the
> conduction band minimum, say at the Gamma point, then the emission spectrum
> only arises from the occupied states at the Gamma point.
> 
> Finally, my question(s) are as follows:
> 
> 1) In order to simulate the RXES spectra near threshold is there a simple tool
> to select by looking at specific energies within the conduction band a list of
> k-points at that energy where there are states available ?
> 
> 2) If I had such a list can I then just provide that to either tetra or qtl in
> order to select the partial density of states (projected along specific axes)
> arising ONLY from those selected k-points ?
> 
> Caveat: I am not a programmer! - but perhaps the tools are already in place ?
> 
> 
> Yours
> 
> Cormac
> --
> Dr. Cormac McGuinness, Lecturer, School of Physics, Trinity College Dublin.
> Phone: +353 1 8963547    Fax: +353 1 6711759    Office: SNIAM 3.17
> 
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