[Wien] exciton trapping

[Laurence Marks]

At least with Wien2k you cannot tell the electrons where to go.

Have you looked at the optic code results?

---------------------------
Professor Laurence Marks
Department of Materials Science and Engineering
Northwestern University
www.numis.northwestern.edu 1-847-491-3996
"Research is to see what everybody else has seen, and to think what nobody
else has thought"
Albert Szent-Gyorgi
 On Mar 1, 2012 2:47 AM, "Fabiana Da Pieve" <fabiana.dapieve at gmail.com>
wrote:

> Hello wien2k users
>
> I am maybe going to ask a trivial or a totally non-sense question, but I
> am trying to do what I can with what I have.
> I know that at the moment BSE calculations with wien2k (and other codes)
> are very computationally demanding, and in any case the BSE part is still
> not released.
>
> In any case, even if it would be released, I think I could not run it on
> my system because it is very heavy.
> However, I would like to find a way (even a very simple one) to see if a
> certain optical excitation would lead to a localized exciton (which
> localizes because of local distortion for example) or if such optical
> excitation would not lead to any distortion. I would like to study this
> because sometimes excitonic transitions could change bond lengths and
> change (slightly, I think) the covalency of a certain bond, and in such
> distortion the exciton could be trapped, which is want I want to see.
>
> So, I was thinking that MAYBE I could have "a first idea" of the eventual
> distortion induce by my optical ideal exciton already at the DFT level in
> the following way:
>
> 1) I remove an electron from one of the external levels of the anion in
> which I believe the hole is created in the file......(ok, very bad thing,
> optical excitations cannot be described as localized on a single site at
> the beginning)
> 2) at this point, either I smear the charge uniformly in space  (or maybe
> I could explicitly put an electron more in the orbital of the cation which
> I know is the acceptor orbital ??)
> 3) instead of running a normal scf calculation, I run a structural
> optimization calculation (keeping the lattice parameters fixed, i.e. moving
> only atoms)
> 4) at the end I analyze the changes in the bond lengths near the atom
>
> Is it correct (at least as a very zero approximation to the problem) ?
> totally wrong ?
> Any suggestions is welcome !
>
> Thanks !
> Fabiana
>
>
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