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 <pu...@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 > _______________________________________________ > Wien mailing list > Wien@zeus.theochem.tuwien.ac.at > http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien > SEARCH the MAILING-LIST at: > http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html -- 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 _______________________________________________ Wien mailing list Wien@zeus.theochem.tuwien.ac.at http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien SEARCH the MAILING-LIST at: http://www.mail-archive.com/wien@zeus.theochem.tuwien.ac.at/index.html
