[Pw_forum] Hubbard_U and Hubbard_alpha

[Matteo Cococcioni]

Dear Hanghui,

Hubbard_alpha is an input parameter used to compute the value of U (PRB 
71 35105 (2005)).
So you don't need to use it for a simple DFT+U calculation if you 
already know the value of U.
J is not implemented in pwscf; U in pwscf (and it's the same on most of 
papers using DFT+U)
corresponds to an effective U_eff = U - J. I have never seen a paper in
literature where the effect of having J treated separately was important 
so I think this the one implemented is
a good enough functional in most of cases.

regards,

Matteo


hanghui chen wrote:
> Dear PWSCF users,
>       I have been recently working on the magnetic properties of
> transitional metal oxides and need to turn on Hubbard U. I found that
> in PWSCF there are two variables Hubbard_U and Hubbard_alpha. In other
> packages like VASP, there are also two variables U (Hubbard U) and J
> (Hund's exchange or Stoner parameter). I would like to know what is
> Hubbard_alpha. Does it have the same meaning as J in VASP? I read the
> menu but could not find the meaning of Hubbard_alpha.
>       Thank you very much.
>
>
> Hanghui Chen
> Department of Physics
> Yale University
> _______________________________________________
> Pw_forum mailing list
> Pw_forum at pwscf.org
> http://www.democritos.it/mailman/listinfo/pw_forum
>   

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