[gpaw-users] Polarizability Tensor

[Michael Walter]

Dear Frank,


2016-06-14 12:15 GMT+02:00 Frank von Horsten via gpaw-users <
gpaw-users at listserv.fysik.dtu.dk>:

> Dear all,
>
> I would like to calculate Raman scattering activities with GPAW. For that
> I need the polarizability tensor.
>
> I saw that there is a get_polarizability() function in the
> DielectricFunction class. However, I am relatively new to GPAW and just
> about to familiarize myself with the program. Hence, I'm not sure how to
> use it correctly.
>
> Can anyone give me some insight how to calculate the elements of the
> polarizability tensor?
>
> To be more specific, let's say we start with an ASE atoms object "atoms"
> and have defined a GPAW calculator "calc":
> 0.) atoms.set_calculator(calc)
> 1.) atoms.get_potential_energy()
> 2.) calc.diagonalize_full_hamiltonian(nbands=X)
> 3.) calc.write("system.gpw",all)
> 4.) df=DielectricFunction('system.gpw',hilbert=not True, eta=0.1, ecut=10,
> frequencies=omega)
> 5.) a0,a=df.get_polarizability(filename=None,direction='x')
>
> Would that be the way to calculate the matrix element \alpha_xx at
> frequency omega?
> If so, I would understand that by changing the direction='y' or 'z' I
> would get \alpha_yy and \alpha_zz. However, I don't know how to obtain the
> off diagonal elements xy etc.
> So I reckon that there is something fundamental, which I misunderstood so
> far.
>
> Any hints would be greatly appreciated! I also saw that there is a new
> ResonantRaman class within ASE. Does anyone know if the is already usable
> or still work in progress?
>

yes, it's working. Basically in the way you intend to use it, but only on
the Kohn-Sham level, which should be ok for most systems.

Michael


>
> Thanks and best wishes,
>
> Frank
>
> _______________________________________________
> gpaw-users mailing list
> gpaw-users at listserv.fysik.dtu.dk
> https://listserv.fysik.dtu.dk/mailman/listinfo/gpaw-users
>



-- 
------------------------------------------
PD Dr Michael Walter
Addresses:
- Fraunhofer IWM, Wöhlerstrasse 11, D-79108 Freiburg i. Br., Germany
  Tel.: +49 761 5142 296
- FIT Freiburg Centre for Interactive Materials and Bioinspired
Technologies, Georges-Köhler-Allee 105, 79110 Freiburg, Germany
  Tel: +49 761 203 95072
email: Michael.Walter at fmf.uni-freiburg.de
www: http://www.functional-nanosystems.uni-freiburg.de/People/PDWalter/group
<http://omnibus.uni-freiburg.de/~mw767>
publications: http://scholar.google.com/citations?user=vlmryKEAAAAJ&hl=en
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://listserv.fysik.dtu.dk/pipermail/gpaw-users/attachments/20160614/463ddc0f/attachment.html>