[Wien] Bethe-Salpeter Equation

[Peter Blaha]

Yes, often BSE for valence optics is even more demanding than BSE for XANES, because
you have more "valence" (occupied) orbitals.

The basis of BSE is formed by the GGA-orbitals, and the size of the Hamiltonian is
Number_of_valence_bands * Number_of_conduction_bands * Number_of_k-points

Eg, with 30 valence and 30 conduction bands and 100 k-points this gives a matrix of
90000x90000, and many screened Coulomb-matrix elements, .....

Typically, we use 512 cores for such calculations .... and still it runs for many days ...

Am 20.04.2011 07:19, schrieb Osama Yassin:
> Dear Prof Blaha,
> 
> When using BSE for optical properties; is it also demanding and requires large clusters?. How can you adapt a BSE code into Wien2k.. i.e linking the an obtained "scf ground 
> state calculations" to "BSE calculations"?.
> 
> Best regards..
> 
> O A Yassin
> 
> 2010/12/1 Peter Blaha <pblaha at theochem.tuwien.ac.at <mailto:pblaha at theochem.tuwien.ac.at>>
> 
>     Dear WIEN2k users,
> 
>     BSE calculations, both for valence excitonic effects or for ELNES/XANES are quite demanding
>     calculations. They require a large cluster with a fast mpi-interconnect (Infiniband).
> 
>     Furthermore, at present the code is not documented and not easy to use, because it requires
>     the understanding of several details, both from the physics point of view as well as from the
>     computational knowledge.
> 
>     For all those reasons, we do not intend to release the BSE code to everybody in the near future.
> 
>     However, if you have a good and physical sound problem, we may be interested in a collaboration
>     and you can contact us directly (either pblaha at theochem.tuwien.ac.at <mailto:pblaha at theochem.tuwien.ac.at> or rolask at theochem.tuwien.ac.at
>     <mailto:rolask at theochem.tuwien.ac.at>)
>     for further details.
> 
>     Best regards
>     Peter Blaha
>     Am 29.11.2010 10:33, schrieb ZhenChen:
>      > Dear Prof. Peter Blaha and all users,
>      > I have read the papers about using BSE to simulate ELNES augmented in Wien2k (Phys. Rev. B 79, 041102R (2009), J. Phys.: Condens. Matter 21, 104205 (2009). ). And I
>     am eager to
>      > know if it will be released in the next Wien2k version, or do you have any plan or time schedule to release the BSE modular?
>      > Thank you in advance!
>      > Best regards!
>      > Zhen Chen
>      > 陈震
>      > ------------------------------
>      > Beijing Laboratory of Electron Microscopy
>      > Institute of Physics
>      > Chinese Academy of Sciences
>      > P. O. Box 603
>      > Beijing 100190, China
>      > Tel: 86-10-82648001
>      >　　　　　　　　 zchen at blem.ac.cn <mailto:zchen at blem.ac.cn>
>      >
>      >
>      >
>      > _______________________________________________
>      > Wien mailing list
>      > Wien at zeus.theochem.tuwien.ac.at <mailto:Wien at zeus.theochem.tuwien.ac.at>
>      > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> 
>     --
> 
>     P.Blaha
>     --------------------------------------------------------------------------
>     Peter BLAHA, Inst.f. Materials Chemistry, TU Vienna, A-1060 Vienna
>     Phone: +43-1-58801-15671 FAX: +43-1-58801-15698
>     Email: blaha at theochem.tuwien.ac.at <mailto:blaha at theochem.tuwien.ac.at> WWW: http://info.tuwien.ac.at/theochem/
>     --------------------------------------------------------------------------
> 
>     _______________________________________________
>     Wien mailing list
>     Wien at zeus.theochem.tuwien.ac.at <mailto:Wien at zeus.theochem.tuwien.ac.at>
>     http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien
> 
> 
> 
> 
> -- 
> Prof Dr Osama Ali Yassin
> Professor of Solid State Physics and ICTP regular associate
> Department of Physics, Faculty of Science
> Taibah University
> Almadeenah Almonawarh
> K. of Saudi Arabia
> 
> 
> 
> _______________________________________________
> Wien mailing list
> Wien at zeus.theochem.tuwien.ac.at
> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien

-- 
-----------------------------------------
Peter Blaha
Inst. Materials Chemistry, TU Vienna
Getreidemarkt 9, A-1060 Vienna, Austria
Tel: +43-1-5880115671
Fax: +43-1-5880115698
email: pblaha at theochem.tuwien.ac.at
-----------------------------------------