[Pw_forum] (Niharika Joshi)

[Matteo Calandra]

Le 24/01/12 09:33, pw_forum-request at pwscf.org a écrit :
> ------------------------------
>
> Message: 2
> Date: Tue, 24 Jan 2012 11:49:00 +0530 (IST)
> From: Niharika Joshi<joshiniharika20 at yahoo.in>
> Subject: [Pw_forum] Occupied states in XAS
> To: "pw_forum at pwscf.org"<pw_forum at pwscf.org>
> Message-ID:<1327385940.93549.YahooMailNeo at web95709.mail.in.yahoo.com>
> Content-Type: text/plain; charset="iso-8859-1"
>
> Hello,
>
> In the xspectra calculation, the option 'cut_occ_states=.false.' will include the occupied states in XAS.
> Why should one consider occupied states in absorption spectra because the transitions are only to empty states. Or have understood it wrong?
> ?-Niharika Joshi

Dear Niharika,

   of course in XAS only empty states are measured. However plotting 
occupied states could
be useful for low energy features (pre-edge region). When for example 
there is not a clear large
gap, it can be difficult to isolate empty from occupied states. This is 
the case in metals or small gap
systems. So it can be useful to look at the full spectrum and see where 
the Fermi level is located.

M.

> (Project student, Indian Institute of Science Education and Research, Pune, India)
> -------------- next part --------------
> An HTML attachment was scrubbed...
> URL: http://www.democritos.it/pipermail/pw_forum/attachments/20120124/bccced8d/attachment-0001.htm
>
> ------------------------------
>
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
>
>
> End of Pw_forum Digest, Vol 55, Issue 39
> ****************************************


-- 
* * * *
Matteo Calandra, Directeur de Recherche (DR2)
Institut de Minéralogie et de Physique des Milieux Condensés de Paris
Université Pierre et Marie Curie, tour 23, 3eme etage, case 115
4 Place Jussieu, 75252 Paris Cedex 05 France
Tel: +33-1-44 27 52 16       Fax: +33-1-44 27 37 85
http://www.impmc.jussieu.fr/~calandra