[Wien] Hartree-Fock and the Hubbard Model

[Luis Ogando]

   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 <delamora at unam.mx>:

> Luis, look for Hubbard Model
>
> NaCl U2
>
>           Pablo
> ------------------------------
> *De:* Wien <wien-bounces at zeus.theochem.tuwien.ac.at> en nombre de Luis
> Ogando <lcodacal at 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 <tran at 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 at 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
>> en at zeus.theochem.tuwien.ac.at/index.html
>>
>>
>
> _______________________________________________
> Wien mailing list
> Wien at 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 at zeus.theochem.tuwien.ac.at/index.html
>
>
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://zeus.theochem.tuwien.ac.at/pipermail/wien/attachments/20161122/d316623d/attachment.html>