[Wien] Confusion in Selecting proper value of Hubbard potential.

[tran at theochem.tuwien.ac.at]

Hi,

I have never heard that the proper value of U is the one when the band gap
starts to decrease. Usually the value of U is chosen such that the
calculated properties (e.g., band gap or magnetic moment) agree with
experiment.

F. Tran

On Sat, 20 Jul 2013, Zaid wrote:

> Respected Users
> 
> 
> I am applying GGA+U technique to considered compounds. In order to select
> proper value of U for specific material, I am changing the value of U from
> 2eV to 10eV with a step of 1eV. I was expecting that on increasing U value
> in the range 2-10eV, a value of U will appear where the corresponding band
> gap will start to decrease instead of increase. That value of U where the
> band gap start to decrease instead of rising will be the proper U value in
> the range 2-10eV.
> 
> I my case the, every time I am getting increasing band gap values on
> increasing U value from 2-10eV with a step of 1eV. Band gap does not
> decrease in the range 2-10eV. Should I increase the range ? May anyone
> suggest that whether my practice of finding U value is right ? If not how
> can I find proper value of U for specific compound ?
> 
> Thank you very much
> 
> Best Regards
> Zaid
>