Thank you Pablo ! I am looking for something introductory like wikipedia. Do you have some reference "in this direction" ? All the best, Luis
2016-11-21 15:25 GMT-02:00 delamora <delam...@unam.mx>: > Luis, look for Hubbard Model > > NaCl U2 > > Pablo > ------------------------------ > *De:* Wien <wien-boun...@zeus.theochem.tuwien.ac.at> en nombre de Luis > Ogando <lcoda...@gmail.com> > *Enviado:* lunes, 21 de noviembre de 2016 11:00:23 a. m. > *Para:* A Mailing list for WIEN2k users > *Asunto:* Re: [Wien] Hartree-Fock and the Hubbard Model > > Dear Prof. Tran, > > I would like to read more about this subject, but, unfortunately, your > link gave me a message like : " Wikipedia does not have an article with > this exact name. " > Please*,* could you suggest another non-specialist reference like > wikipedia ? > Thank you, > Luis > > 2016-11-20 13:28 GMT-02:00 <t...@theochem.tuwien.ac.at>: > >> Hi, >> >> DFT+U is a cheap but rather rough approximation of HF. >> Beside this, there is also the difference that in DFT+U, the Coulomb >> operator is attenuated in order to account for the screening due to >> correlation. In HF, no correlation is included. >> In hybrids, the screening is included by using only ~25% of HF exchange >> (and there is also correlation coming from a LDA/GGA correlation term). >> >> Hybrid, onsite-hybrid and DFT+U are more or less the same, >> since all of them are one-electron methods and mix HF with LDA/GGA. >> As Karel said, they are better than LDA/GGA, but can not reproduce >> the experimental observations that are beyond the one-electron methods. >> DMFT is better since it is a beyond one-electrons method. >> >> Read that: >> https://en.wikipedia.org/wiki/LDA+U >> >> FT >> >> >> On Wed, 16 Nov 2016, delamora wrote: >>> >>> >>> Dear Fabien Tran and Karel Vyborny, >>> >>> Thanks for your comments. >>> >>> >>> What I want to know is if the Hartree Fock exchange is what the Hubbard >>> U is >>> trying to model >>> >>> What I know is that for strong intraatomic repulsion, 3d and 4f, the >>> Hubbard >>> U gives good results, although the U is a parameter. >>> >>> But for intermediate intraatomic repulsion, 4d, 5d, 5f then more >>> expensive >>> methods are needed, such as DMFT >>> >>> So, if this is the case that the Hartree Fock exchange is what the >>> Hubbard U >>> is trying to model then the hybrid functionals would do a better job. >>> >>> So, my question is; What are the Hubbard U and DMFT trying to model? >>> >>> >>> Cheers >>> >>> Pablo de la Mora >> >> >> _______________________________________________ >> Wien mailing list >> Wien@zeus.theochem.tuwien.ac.at >> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien >> SEARCH the MAILING-LIST at: http://www.mail-archive.com/wi >> e...@zeus.theochem.tuwien.ac.at/index.html >> >> > > _______________________________________________ > Wien mailing list > Wien@zeus.theochem.tuwien.ac.at > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien > SEARCH the MAILING-LIST at: http://www.mail-archive.com/ > wien@zeus.theochem.tuwien.ac.at/index.html > >
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