[Pw_forum] Theoretical XES spectra

[Alexander Shaposhnikov]

I want to use pwscf for the calculation of  theoretical XES spectra
for some materials (SiO2, Si3N4 and others) 
where it is not always possible to use simple model 
of one predominant transition type -for example,
in Si L2,3 spectra (transition to Si 2p states) both Si 3S 
and Si 3D states make contribution. Even worse, some results indicate 
that non-local transitions are also non-negligible.

So i need to explicitly
calculate dipole matrix element for this transition.

Could somebody point me to some theoretical background, specific for
planewaves and pseudopotentials?

Thanks in advance.