[Wien] Adding excitonic effects

[Gavin Abo]

FYI, there is a separate BSE code for WIEN2k called BSE at WIEN2k.

It seems to require a cluster with hundreds of cores and a large amount 
of memory as described on slide 23 in the document at:

http://www.wien2k.at/reg_user/textbooks/WIEN2k_lecture-notes_2013/DFT_advanced.pdf

It cannot be downloadable from Dr. C. Ambrosch-Draxl's old website 
anymore as it no longer exists.  However, you should be able to still 
read about it on wayback:

https://web.archive.org/web/20120415092421/http://amadm.unileoben.ac.at/codes_wien2k.html

If your interested in it, I think you can try requesting it from Dr. R. 
Laskowski:

http://www.mail-archive.com/wien%40zeus.theochem.tuwien.ac.at/msg03642.html

On 5/16/2015 12:28 AM, Xavier Rocquefelte wrote:
> To properly describe an exciton, which is a two-particle entitie, you 
> need a two-particle theory at least.
> DFT is a one particle theory, thus it is not suited to properly 
> describe excitonic effects.
> For solids you must use the Bethe Salpeter Equation (BSE) which is 
> implemented in other codes and very expensive in terms of 
> computational time and memory. Another strategy is to mimick the 
> effect of the exciton on the optical properties using DFT and a 
> corehole approach. This last strategy is pragmatic and not exact, but 
> it allows to deals with this 2-particle problem using a one-particle 
> approach in a mean-field manner. Usually, a half corehole is used. It 
> corresponds to the Slater transition state and it gives nice results 
> in general. What kind of transtions are your doing? Does it implies 
> core states? If yes you can easily remove half an electron in the file 
> case.inc. If the transition is from valence states, the problem is 
> more tricky to solve.
> Best Regards
> Xavier
>
>
> Dileep Krishnan <dileep at jncasr.ac.in> a écrit :
>
> > Hi Users and Developers,
> >
> > I was calculating optical properties by OPTIC program. How can I add
> > excitonic effects into the calculation?
> >
> > --
> > Dileep Krishnan,
> > Int. Ph. D Student,
> > International Centre for Materials Science (ICMS),
> > Jawaharlal Nehru Centre for Advanced Scientific Research (JNCASR),
> > Jakkur, Bangalore-560064,
> > INDIA.