[Pw_forum] LDA+U calculations to get U and J

[Gianluca Giovannetti]

Dear Matteo,

thank you for the link.
now it is fine.
i can calculate U with your scheme. :-)

what about J ?

cheers,

Gianluca

On Mon, Feb 15, 2010 at 2:45 AM, Matteo Cococcioni <matteo at umn.edu> wrote:

>
> Dear Gianluca,
>
> here is the link to a tutorial on how to compute the U:
>
> http://media.quantum-espresso.org/santa_barbara_2009_07/index.php
>
> This method uses the atomic occupations defined as in the PRB '05 paper
> you refer to in your email.
>
> For sure one could use Wannier functions ainstead of atomic orbitals.
> HoweverI have no direct experience with that
> so I cannot tell you how to do this in practice.
>
> regards,
>
> Matteo
>
> Gianluca Giovannetti wrote:
>
> > Dear All,
> >
> > i would like to calculate the U and J for a given material Fe based.
> > I can do LDA+U calculations without problems is such system using PW.
> >
> > The paper "Phys. Rev. B 71, 035105 (2005)" well explains how to
> > calculate the parameter U.
> > i have however troubles in setting the input files to do the
> calculations.
> > could some examples be provided?
> >
> > I have also another question.
> >
> > In the current distribution of PW in the directory PP there is a file
> > wannier_ham.f90.
> > I believe it is referring to the paper:
> >
> > http://xxx.lanl.gov/pdf/0801.3500
> >
> > The subroutines are reading wfs and eigenvalues of a given
> > self-consistent calculation and they calculate the Hamiltonian in
> > Wannier basis set.
> > This gives the possibility to calculate on-site energy of given d states.
> > If now we change the occupancy at a given site by the flag
> > Hubbard_alpha() and we recalculate the Hamiltonian in Wannier basis
> > set for such self-consistent calculation, the variation of eigenvalues
> > respect to the occupations should give the U and J parameters.
> > Is this correct?
> > Is this the procedure used in the mentioned paper?
> >
> > thank you.
> >
> > cheers,
> >
> > Gianluca
> >
> > ------------------------------------------------------------------------
> >
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>
>
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> Matteo Cococcioni
> Department of Chemical Engineering and Materials Science,
> University of Minnesota
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