[Pw_forum] Raman intensity and LDA+U

[Stefano de Gironcoli]

dear PWSCF users,

On Mon, 10 Mar 2003, zyli wrote:

> 
>      It's said that the PWSCF can determine the Hubbard U
> parameter in LDA+U calculations automaticaly. But in the 
> INPUT.PW I also find that I need to give Hubbard_U as a 
> parameter, why?
> 

Where is it said that PWSCF can determine the Hubbard U parameter 
AUTOMATICALLY ?
It is not true. Please let me know where this is stated so we can 
correct this error.

PWSCF can perform LDA+U calculations using an input value for U
specified using the Hubbard_U variables in &system namelist.
PWSCF can compute a value for U from the variation of the localized
state occupancy due to a localized perturbing potential specified
through the Hubbard_alpha variables in &system namelist.

Details about the idea are contained in Matteo Cococcioni's PhD thesis
and in a paper we are currently writing.
Defining automatic this procedure is, to say the least, an exageration.

Stefano de Gironcoli