Dear Professor Seitsonen
Thanks for your consideration and sorry so late answer Bests. Yavar On Sun, Dec 30, 2012 at 7:50 AM, Ari P Seitsonen <Ari.P.Seitsonen at iki.fi>wrote: > > Dear Yavar Taghipour Azar, > > From what I know, only the energy eigenvalue HOMO should have a physical > meaning - the ionisation energy - but also it would naturally require the > usage of the exact exchange-correlation functional. All the rest relies on > the empirism, that they seem to correspond quite reasonably the > qualitative, often also quantitative results from the experiments and > chemical picture/intuition, or the more accurate theoretical methods > (quantum chemical approach like coupled-cluster methods, many-body methods > like GW and Bethe-Salpeter equations). So there is no theoretical > foundation for the usage of the Kohn-Sham orbitals and eigenvalues, just > the overall general agreement and convenience (which can sometimes be read > also as "lazyness" ;). > > Hopefully this clarifies your confusion at least partially. The > textbooks should discuss this also this more "practical" aspect, strange if > they don't. I don't remember when/if this topic has been discussed already > before (mailing list/FAQ), sorry. > > Greetings from Zurich, > > apsi > > -=*=-=*=-=*=-=*=-=*=-=*=-=*=-=***=-=*=-=*=-=*=-=*=-=*=-=*=-=*=** > -=*=-=*=-=*=-=*=- > Ari P Seitsonen / Ari.P.Seitsonen at iki.fi / http://www.iki.fi/~apsi/ > Physikalisch-Chemisches Institut der Universitaet Zuerich > Tel: +41 44 63 54 497 / Mobile: +41 79 71 90 935 > > > > On Sun, 30 Dec 2012, Yavar Taghipour Azar wrote: > > >> Dear QE user >> >> As mentioned in some text books (for eample, A Chemist?s Guide to Density >> Functional Theory); >> The orbitals satisfying Kohn-Sham equation have no physical significance >> and their only connection >> to the real world is that the sum of their squares add up to the exact >> density. >> >> by considering this, I cant understand physical relevance of isosurfaces >> which plotted in pw postprocess and >> the real molecular orbitals (HOMO, LUMO, LUMO+1................). >> >> thanks in advance >> >> Yavar Taghipour Azar >> >> Condensed Matter Section, AEOI >> >> Tehran, Iran >> > > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://pwscf.org/mailman/listinfo/pw_forum > -------------- next part -------------- An HTML attachment was scrubbed... URL: http://pwscf.org/pipermail/pw_forum/attachments/20130123/e24961b8/attachment.html
