[Wien] Choice of Coulomb Energy

[Laurence Marks]

Some suggestions:

a) Use "literature" values from others. Of course, if the other papers
were wrong then so are your results.
b) Use the method in
http://www.wien2k.at/reg_user/textbooks/Constraint_U.pdf -- not so
easy!
c) Use a reference, either thermodynamic data for the heat of
formation of comparable system or (maybe) spectroscopic data. For
instance you could use the "U" that is "best" for CeO2, where you have
to be ready to defend your choice of what "best" means.

N.B., personally I consider LDA+U to be relatively obsolete and would
always use the on-site -eece as a more general method. You calibrate
this via a reference, in my opinion.

On Mon, Jun 17, 2013 at 8:30 AM, Uday <puday at iitk.ac.in> wrote:
> Dear Wien2k users and Prof. Blaha,
> I am working on a "Ce" based magnetic system. I tried to do LSDA+U with
> different values of U from 0 to 6 eV for Ce-4f sate. U=0 eV gives the
> minimum energy and total energy for the system increases as we increase U
> value. Also the DOS for Ce-4f keeps on shifting with increasing U. My
> question is how to choose a correct U value for a system when a
> spectroscopic data is missing?
> Any help will be appreciated.
>
> Regards,
> Uday
> Dept. of Physics
> IIT Kanpur
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-- 
Professor Laurence Marks
Department of Materials Science and Engineering
Northwestern University
www.numis.northwestern.edu 1-847-491-3996
"Research is to see what everybody else has seen, and to think what
nobody else has thought"
Albert Szent-Gyorgi