[Wien] Gap calculated with GGA+U, mBJ and HF

[tran at theochem.tuwien.ac.at]

The answer given by GW, GGA+U and mBJ is probably the correct one,
but one has to be careful for strongly correlated systems, since
it is easy to get a solution that is not the ground state one.


On Monday 2017-08-07 13:57, Wien2k User wrote:

>Date: Mon, 7 Aug 2017 13:57:45
>From: Wien2k User <wien2k.user at gmail.com>
>Reply-To: A Mailing list for WIEN2k users <wien at zeus.theochem.tuwien.ac.at>
>To: A Mailing list for WIEN2k users <wien at zeus.theochem.tuwien.ac.at>
>Cc: Victor Luaña <victor at fluor.quimica.uniovi.es>
>Subject: Re: [Wien] Gap calculated with GGA+U, mBJ and HF
>
>Thank you Dr.Víctor Luaña and Dr  Karel Vyborny
>
>
>My problem is that I found two results that give different electronic behavior 
>
>Depending on Dr. Fabien Tran response, HF overestimate the gap.
>And I think GW, GGA+U and mBJ potential are better adapt to estimate the gap and I think their results for the studied material indicates that it is semimetal pending confirmation.
>
>2017-08-07 12:50 GMT+02:00 Víctor Luaña Cabal <victor at fluor.quimica.uniovi.es>:
>      On Mon, Aug 07, 2017 at 11:02:19AM +0200, Wien2k User wrote:
>      > But for my problem is what I have to say that the material is semimetalic
>      > since this result is obtained with GW, GGA+U and mBJ?.
>      > Or I have to present all the results even those obtained by HF and I would
>      > say that the calculations gave different results pending confirmation of
>      > the experiment?
>      >
>
>      You adopt the position that theory is only justified if it is in
>      agreement with an experiment. There are many people adopting that point
>      of view, but it is *not* the only one. An excellent article can examine
>      deeply which are the factors that control the property you are interested
>      in, for instance. Or explaining why those factors are important. A
>      tinkertoy model can be the main contribution to an extraordinary Physical
>      Review Letters.
>
>      Remember that theory contributes to knowledge, and only when theory is
>      so well polished that it can compete in agreement and precision with
>      experimental measurements it can contribute to databases of properties.
>
>      Being realistic,  a careful examination of the articles published
>      lately (a few years) in the journal you want to send your research is
>      the best step in determining the orientation of your contribution.
>      Many contributions tend to use "results pending confirmation" and the
>      referee answer may be 'let us wait to the experiments' ... ;-)
>
>      Best regards,
>                   Víctor Luaña
>
>      --
>          .  .    "Half of the US people use twitter to form its opinion and half
>         / `' \   also elect the US president. I only hope they are not the same
>        /(o)(o)\  half". --From a sentence by Gore Vidal
>       /`. \/ .'\
>      /   '`'`   \
>      |  \'`'`/  |
>      |  |'`'`|  |
>       \/`'`'`'\/
>      ==(((==)))===================================+===========================
>      ! Dr.Víctor Luaña, in silico chemist & prof. !
>      ! Departamento de Química Física y Analítica !
>      ! Universidad de Oviedo, 33006-Oviedo, Spain !
>      ! e-mail:  <victor at fluor.quimica.uniovi.es>  !
>      ! phone: +34-985-103491  fax: +34-985-103125 !
>      +--------------------------------------------+
>       GroupPage: <http://azufre.quimica.uniovi.es/>
>       Articles:  <http://scholar.google.com/citations?user=Ibl1BWAAAAAJ&hl=es>
>       git-hub:   <https://github.com/aoterodelaroza>
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>
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