[Pw_forum] Raman intensity with or without ASR
Paolo Giannozzi
paolo.giannozzi at uniud.it
Mon Feb 2 11:05:04 CET 2015
On Mon, 2015-02-02 at 09:55 +0100, Antoine JAY wrote:
> I have calculated a lot of Raman Spectra with QE which give very accurated
> results.
good to know
> But when I try to calculate Raman intensities with the eigenvectors
> obtained after ASR (crystals) results aren't that accurate. The ASR do not
> change my Raman frequencies, give 0 acoustic frequencies and change a bit
> eigenvectors as expected.
this doesn't sound right to me: why should Raman intensities change a
lot if eigenvectors don't? By the way, try asr='simple' before trying
other more sophisticated forms of ASR.
Paolo
> Question: Why do I have to take eigenvectors which are calculated BEFORE
> the ASR in the calcul of the intensity ?
> (Equ.2 in Lazzeri, Mauri, PRL 90036401-1(2003))
>
> Thanks a lot
>
> Antoine JAY
> Doctorant (PhD student)
> Laboratoire des Solides Irradiés
>
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Paolo Giannozzi, Dept. Chemistry&Physics&Environment,
Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
Phone +39-0432-558216, fax +39-0432-558222
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