A general comment: you may want to use the onsite exact-exchange instead of LDA/GGA+U. It is less sensitive to the precise environment. However, in my experience this (and LDA/GGA+U) is better just of d-orbitals, and less effective for O p levels.
On Tue, Jun 26, 2012 at 10:47 AM, Shamik Chakrabarti <shamikiitkgp at gmail.com > wrote: > Dear Haranath Ghosh, > > Yes U can be used for p orbital of oxygen...but what value of U > you are going to use that depends on the system and the problem you are > studied.....& also what error you are getting??...that is not clear from > your mail > > with regards, > > On Tue, Jun 26, 2012 at 6:48 PM, Haranath Ghosh <ghoshharanath at > yahoo.com>wrote: > >> Dear experienced Users and developer Wien2k, >> >> Is it possible to use U value for Oxygens with l=1 orbitals. I always >> get error. Thanks for your response. >> >> with best regards, Haranath Ghosh >> >> --- On *Tue, 6/26/12, shamik chakrabarti <shamikphy at gmail.com>* wrote: >> >> >> From: shamik chakrabarti <shamikphy at gmail.com> >> Subject: Re: [Wien] A basic question about GGA+U approach >> To: "A Mailing list for WIEN2k users" <wien at zeus.theochem.tuwien.ac.at> >> Date: Tuesday, June 26, 2012, 6:37 PM >> >> >> Dear Prof. Peter Blaha, >> >> Thank you very much for your reply. I got my answer. >> >> with best regards, >> >> On Tue, Jun 26, 2012 at 11:19 AM, Peter Blaha < >> pblaha at >> theochem.tuwien.ac.at<http://us.mc1606.mail.yahoo.com/mc/compose?to=pblaha >> at theochem.tuwien.ac.at> >> > wrote: >> >> Yes, U depends on the type of atom, but of course also on the specific >> compound. >> For metallic Fe the U should be in the range of 0-2 eV at most, for some >> insulating compound with very localized states, it may go up to even 4-6 >> (maybe even 8) eV. >> >> Am 26.06.2012 06:42, schrieb shamik chakrabarti: >> >> Dear wien2k users, >> >> We generally choose the value of U by fitting it with >> experimental band gap or by calculating it through linear response >> method. Now my question is that whether U is element specific or depends >> on the composite in which the element reside? (*if I consider same >> >> magnetic configuration for all the composites I am referring here...as >> antiferromagntism do produce a band gap even without applying any U*) >> >> >> To make it more clear, say for Fe d, I have seen in literature, people >> have used U=4.5 to 5 eV......in some of our calculation we have even >> used U=6 eV for Fe d to obtain better electronic structure having closer >> match with experimental observation. Hence it looks that U for Fe d >> orbital can have value ranging from 4.5-6 eV...& that mean U is not >> element specific rather it depends on the composite in which the element >> exist (I again want to insist that if I consider same magnetic >> configuration for all the composites). Am I right? >> >> with regards, >> >> -- >> Shamik Chakrabarti >> Senior Research Fellow >> Dept. of Physics & Meteorology >> Material Processing & Solid State Ionics Lab >> IIT Kharagpur >> Kharagpur 721302 >> INDIA >> >> >> ______________________________**_________________ >> Wien mailing list >> Wien at >> zeus.theochem.tuwien.ac.**at<http://us.mc1606.mail.yahoo.com/mc/compose?to=Wien >> at zeus.theochem.tuwien.ac.at> >> http://zeus.theochem.tuwien.**ac.at/mailman/listinfo/wien<http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien> >> >> >> -- >> Peter Blaha >> Inst.Materials Chemistry >> TU Vienna >> Getreidemarkt 9 >> A-1060 Vienna >> Austria >> +43-1-5880115671 >> >> >> ______________________________**_________________ >> Wien mailing list >> Wien at >> zeus.theochem.tuwien.ac.**at<http://us.mc1606.mail.yahoo.com/mc/compose?to=Wien >> at zeus.theochem.tuwien.ac.at> >> http://zeus.theochem.tuwien.**ac.at/mailman/listinfo/wien<http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien> >> >> >> >> >> -- >> Shamik Chakrabarti >> Senior Research Fellow >> Dept. of Physics & Meteorology >> Material Processing & Solid State Ionics Lab >> IIT Kharagpur >> Kharagpur 721302 >> INDIA >> >> -----Inline Attachment Follows----- >> >> >> _______________________________________________ >> Wien mailing list >> Wien at >> zeus.theochem.tuwien.ac.at<http://us.mc1606.mail.yahoo.com/mc/compose?to=Wien >> at zeus.theochem.tuwien.ac.at> >> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien >> >> >> _______________________________________________ >> Wien mailing list >> Wien at zeus.theochem.tuwien.ac.at >> http://zeus.theochem.tuwien.ac.at/mailman/listinfo/wien >> >> > > > -- > Shamik Chakrabarti > Senior Research Fellow > Dept. of Physics & Meteorology > Material Processing & Solid State Ionics Lab > IIT Kharagpur > Kharagpur 721302 > INDIA > -- 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 -------------- next part -------------- An HTML attachment was scrubbed... URL: <http://zeus.theochem.tuwien.ac.at/pipermail/wien/attachments/20120626/8ea7d727/attachment.htm>