[Pw_forum] x-ray spectra with "Fermi-Dirac" electronic smearing., (Huolin Xin)

[Matteo Calandra]

 >Dear developers,

 >Since when did quantum espresso start to offer XANEFS calculations? I
 >remember I sent an email on this forum half of a hear ago to ask
 >whether anyone is interested in developing an EELS calculation plugin.
 >I got no response.


Dear Huolin Xin,

  I think it is roughly 1 year that the XSpectra package is included in 
the CVS version and maybe somewhat less (I don't quite remember) that it 
is included in the official distribution.
However, you should be careful with EELS. XSpectra calculates
K-edge XAS (both dipolar and quadrupolar terms).
EELS is similar to XAS but not identical. In particular the angular
dependence of EELS spectra is not purely dipolar but there is a monopole 
term (that usually is assumed negligible even when it is not).
So using the XAS dipolar simulations to interpret EELS spectra must be 
done "cum grano salis".
We have planned to include EELS calculation in XSpectra, however we have 
not yet started.

M.
-- 
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Matteo Calandra, Charge de Recherche (CR1)
Institut de Minéralogie et de Physique des Milieux Condensés de Paris
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