[Octopus-users] linear response

[Alberto Castro]

Hi,

Yes, since some time ago the Casida calculation is performed always; the
Petersilka approximation is performed before, so if you are happy with it,
you can just kill the run. The reason is that we found out that, being a
little bit smart, solving the full Casida equaitions does not take that
much time as compared to doing only the Petersilka approximation, so we
decided that there was no reason not to do it (especially since it turns
out that most of the times the Petersilka approximation is bad).

And about the second point, yes, the oscillator strengths are not
calculated for the Petersilka solutions. There is a big FIXME written in
the source code, waiting for someone to fill the gap. I will add it to the
TODO list for the next release.

Regards,

Alberto.

On Thu, 1 Feb 2007, Daniele Varsano wrote:

> Hi guys,
> I'm Running octopus, version 2.1pre1,
> a version I download some months ago.
> I just need to calculate eigenvalues
> differences, or Petersilka excitation
> energies.
> I realized that oct-excite does not
> exist anymore, and the main octopus
> does it with the
> "CalculationMode = casida"
>
> There is any variable to set
> equivalent to the old:
> LinPetersilka or LinEigenvalues?
>
> ..just to avoid the heavy Casida
> calculation.
>
> Moreover in the /linear/petersilka
> and /linear/eps_diff
> I get excitation energies, but
> all with zero oscillator strength,
> is it a known bug?, or I'm doing
> something wrong?
>
> In the input I just set the
> KS function I want to include.
> LinearResponseKohnShamStates = "20-41"
>
> Hope someone can help me.
>
> Daniele
>
>
> --
> Daniele Varsano
> Natl. Center S3 INFM-CNR
> c/o Dipartimento di Fisica, Universita' di Modena e Reggio E.
> Via Campi 213/A, 41100 Modena, Italy
> e-mail: varsano.daniele at unimo.it
> URL: http://www.nanoscience.unimo.it
> http://www.s3.infm.it
> ph: +39-059-205-5315 fax: +39-059-205-5651
>
> _______________________________________________
> Octopus-users mailing list
> Octopus-users at tddft.org
> http://www.tddft.org/mailman/listinfo/octopus-users
>

======================================================================
Dr. Alberto Castro

Institut fur Theoretisch Physik, Freie Universitat Berlin.
Arnimallee, 14, Berlin 14195 (Deutschland)

Tel:   +49 030 83853028
Fax:   +49 030 83855258
skype: alberto_c_barrigon
email: alberto at physik.fu-berlin.de
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