[Wien] unscreened hubbard parameter U

[Antoine V]

Although I am not specialist in the explicit calculation of the U 
parameter, my simple remark is that 4.5 eV is a pretty good value for 
U(Fe) in LDA+U schemes.
See also the excellent paper by Zhou et al., PRB 70, 235121 (2004).
"Unscreened" atomic values might be as high as 24 eV (ionization 
energy), a value useless for LDA+U calculations, besides. Maybe lstart 
is enough to calculate ionization energies of atoms.

Amene Nouri a écrit :
> Hello WIEN2k users
> I have a question about using the method introduced by Madsen and Novak for calculation hubbard parameter of LDA+U. Do you think it is correct to calculate unscreened atomic U?
> I used this method by using supercells with 20 bohr lattice constant. The result that I found is one order of magnitude smaller than what I expected. For example I found it 4.5 eV for Fe but the correct one is 24 ev.
> Do you have any suggestion?
> Thanks in advance
>
>
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