[Pw_forum] xspectra calculation

[Matteo Calandra]

>Dear Matteo,

>So when we just do the dipolar part, we don't need to care about the
>k vector, right?

yes, it is not used.

>Besides, in order to  compare with an experimental spectrum, is it necessary to cut
>the occupied state below Fermi energy level within our Xspectra calculation ?
>In that case, we should set "cut_occ_states" = .true. and 
>"ef_r" equal to the fermi energy we got in the scf calculation. Is it?

Yes. However if you have a small gap insulator, introduction of a 
core-hole can lead to a metallic system (close the gap). In this case it is
not clear where to cut. Actually in this case the static core-hole 
approximation is probably incorrect.
For metals it is even worst.

M.

Best regards,

Min Wu
2010-10


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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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