XAS: Relation Between Band Energies and Energy in Dielectric Function Output

[nsolan]

Hi,

I am trying to apply a broadening to my XAS spectra dependent on the energy relative to the fermi energy. Therefore, I would like to know the corresponding value of the fermi energy in reference to the energies in the printed dielectric function output. On the wiki, I found "The energies of the excitations are with respect to the energy levels of the core electron of interest," however, when I take the difference between the fermi energy and the core-state eigenenergy I noticed there is still ~7-10 eV offset between this value and the absorption onset of the XAS spectrum, so I am still missing a factor. How do I directly calculate the corresponding band energy values in reference to the outputted dielectric function energies?

Thanks!

[alexey.tal]

Dear nsolan,

Could you please provide the input and output files for your calculations so that I can better understand the context?

In a semiconducting system, the core-state excitation occurs into the lowest unoccupied bands, so the offset you mentioned could simply be the energy difference between the Fermi level and the lowest conduction-band state.

Best,
Alexey