[Wien] exciton trapping

[Fabiana Da Pieve]

Hello

thanks for the suggestion ! I wanted to try to avoid it because my
sistem is superheavy and...already normal ground state calculations
are quite demanding, but yes, you are right.

Thanks

2012/3/1, Laurence Marks <L-marks at northwestern.edu>:
> 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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>>
>