Dear All,<br><br>thank you for the reply. i appreciate it.<br><br>i need U and J for a DMFT (homemade) code.<br>this is the reason i would prefer to calculate U and J via Wannier formalism.<br>Wannier functions i have calculated including d and p states/bands in order to have more localized states and i can have eigenvalues for self-consistent unperturbed (alpha=0) and perturbed (alpha finite) runs.<br>
i don`t understand if U and J calculated via derivates of eigenvalues respect occupancies of this two runs are correct.<br>what is your opinion?<br><br>i have the feeling that i should take care to extrapolate for different sizes of my system in what i`m doing.<br>
<br>What do you mean by "very similar but another procedure"?<br><br>thank you.<br><br>Gianluca<br><br><br><br><div class="gmail_quote">On Mon, Feb 15, 2010 at 10:10 AM, Dmitry Korotin <span dir="ltr"><<a href="mailto:dmitry@korotin.name">dmitry@korotin.name</a>></span> wrote:<br>
<blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;">Dear Gianluca,<br>
<div class="im"><br>
> i would like to calculate the U and J for a given material Fe based.<br>
> I can do LDA+U calculations without problems is such system using PW.<br>
<br>
</div>If you are going to use U and J within original QE code you should<br>
calculate U and J for atomic states as Matteo Cococcioni suggests.<br>
<div class="im"><br>
> In the current distribution of PW in the directory PP there is a file<br>
> wannier_ham.f90.<br>
> I believe it is referring to the paper:<br>
><br>
> <a href="http://xxx.lanl.gov/pdf/0801.3500" target="_blank">http://xxx.lanl.gov/pdf/0801.3500</a><br>
><br>
> The subroutines are reading wfs and eigenvalues of a given self-consistent<br>
> calculation and they calculate the Hamiltonian in Wannier basis set.<br>
> This gives the possibility to calculate on-site energy of given d states.<br>
> If now we change the occupancy at a given site by the flag Hubbard_alpha()<br>
> and we recalculate the Hamiltonian in Wannier basis set for such<br>
> self-consistent calculation, the variation of eigenvalues respect to the<br>
> occupations should give the U and J parameters.<br>
> Is this correct?<br>
> Is this the procedure used in the mentioned paper?<br>
<br>
</div>In the mentioned paper was used very similar but another procedure.<br>
With use of the flag Hubbard_alpha() you are able to change occupancy<br>
of a pure atomic (pseudoatomic) orbital. If Wannier function differs<br>
noticeably from pure atomic state standart procedure is not suitable.<br>
<br>
--<br>
Best regards,<br>
Dmitry Korotin<br>
<br>
Ph. D. Student,<br>
Institute of Metal Physics<br>
S. Kovalevskaya, 18<br>
620041 Ekaterinburg GSP-170<br>
Russia<br>
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