Dear Matteo,<br><br>thank you for the link.<br>now it is fine. <br>i can calculate U with your scheme. :-)<br><br>what about J ?<br><br>cheers,<br><br>Gianluca<br><br><div class="gmail_quote">On Mon, Feb 15, 2010 at 2:45 AM, Matteo Cococcioni <span dir="ltr"><<a href="mailto:matteo@umn.edu">matteo@umn.edu</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;"><br>
Dear Gianluca,<br>
<br>
here is the link to a tutorial on how to compute the U:<br>
<br>
<a href="http://media.quantum-espresso.org/santa_barbara_2009_07/index.php" target="_blank">http://media.quantum-espresso.org/santa_barbara_2009_07/index.php</a><br>
<br>
This method uses the atomic occupations defined as in the PRB '05 paper<br>
you refer to in your email.<br>
<br>
For sure one could use Wannier functions ainstead of atomic orbitals.<br>
HoweverI have no direct experience with that<br>
so I cannot tell you how to do this in practice.<br>
<br>
regards,<br>
<br>
Matteo<br>
<div><div></div><div class="h5"><br>
Gianluca Giovannetti wrote:<br>
<br>
> Dear All,<br>
><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>
> The paper "Phys. Rev. B 71, 035105 (2005)" well explains how to<br>
> calculate the parameter U.<br>
> i have however troubles in setting the input files to do the calculations.<br>
> could some examples be provided?<br>
><br>
> I have also another question.<br>
><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<br>
> self-consistent calculation and they calculate the Hamiltonian in<br>
> 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<br>
> Hubbard_alpha() and we recalculate the Hamiltonian in Wannier basis<br>
> set for such self-consistent calculation, the variation of eigenvalues<br>
> respect to the occupations should give the U and J parameters.<br>
> Is this correct?<br>
> Is this the procedure used in the mentioned paper?<br>
><br>
> thank you.<br>
><br>
> cheers,<br>
><br>
> Gianluca<br>
><br>
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Matteo Cococcioni<br>
Department of Chemical Engineering and Materials Science,<br>
University of Minnesota<br>
421 Washington Av. SE<br>
Minneapolis, MN 55455<br>
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