this is what comes out from the calculation (U(O) > U(Ni)). whether it's reasonable to apply U on O or not, I'm not sure.
I think the U shouldn't be used on states that are completely occupied. Matteo ali kazempour wrote: > Dear Matteo > This means that hubbard parameter for oxygen is large (grater than > Ni). Is it correct or originate from another challenge? > thanks > > Ali Kazempour > Physics department, Isfahan University of Technology > 84156 Isfahan, Iran. Tel-1: +98 311 391 3733 > Fax: +98 311 391 2376 Tel-2: +98 311 391 2375 > > --- On *Tue, 8/4/09, Matteo Cococcioni /<matteo at umn.edu>/* wrote: > > > From: Matteo Cococcioni <matteo at umn.edu> > Subject: Re: [Pw_forum] U for Oxygen > To: "PWSCF Forum" <pw_forum at pwscf.org> > Date: Tuesday, August 4, 2009, 6:59 AM > > > > Dear Ali, > > > > ali kazempour wrote: > > Dear Matteo > > I used your comment and followed your example for NiO and I > succeed > > to get U for TiO2. But in file Ur16.out I see three column . > > > > I don't have any three column section in any of my files. so if > you want > me to help you you have to report at least a section of your output > file. This is a good habit actually in consideration of the fact that > this is not a private conversation (I would have asked you in any > case > as I don't remember by heart the format of any file) between me > and you > but a message to the forum and you want other people to understand > what you are saying. > > > The first is number of atom in supercell , second is U value for Ni > > atom and I don,t know the third? does the third belong to U value > > for Oxygen or not? Because the third column kas big value? > > > > > > another question is for isolated atom Hubbard parameter. What do > you > > expect about the value of U for Isolated atom? Is this big value > > (greater than 10 eV) or it would be tiny value? > > > > I think it will be meaningless for the reasons I explained in my last > email. To obtain a meaningful number for the isolated atom you > probably > have to abandon the idea to use a perturbation in the potential and > change instead the number of electrons directly. This means you will > have to do calculations on atoms having fractional charges which > requires additional corrections if you use a code designed for > periodic > systems (crystals). However I have never done this isolated atom > calculation of U before so I don't have more details about it. > I see (from a private email) you are thinking of computing U for the > isolated atom and to obtain a value for the crystal just by > dividing by > the epsilon_inft. the method is proposed in > > http://link.aps.org/doi/10.1103/PhysRevB.74.045202 > > (which I haven't re-read yet). > > I see a couple of problems: > > 1) (not important for ZnO). suppose you have Fe3O4 with Fe2+ and > Fe3+. > these Fe ions likely have different U. how do you obtain > a different number from the atomic code? would you do the calculation > for isolated Fe2+ and Fe3+? > > 2) how do you get epsilon? since it's a linear response property I > don't > think its calculation is any cheaper than the direct calculation of U. > > regards, > > Matteo > > > should we choose for running the script for isolated atom only > gamma > > point or we have to choose a fine mesh? > > thanks a lot > > > > > > Ali Kazempour > > Physics department, Isfahan University of Technology > > 84156 Isfahan, Iran. Tel-1: +98 311 391 3733 > > Fax: +98 311 391 2376 Tel-2: +98 311 391 2375 > > > > --- On *Sun, 8/2/09, Matteo Cococcioni /<matteo at umn.edu > </mc/compose?to=matteo at umn.edu>>/* wrote: > > > > > > From: Matteo Cococcioni <matteo at umn.edu > </mc/compose?to=matteo at umn.edu>> > > Subject: Re: [Pw_forum] occupation > > To: "PWSCF Forum" <pw_forum at pwscf.org > </mc/compose?to=pw_forum at pwscf.org>> > > Date: Sunday, August 2, 2009, 8:31 AM > > > > > > Dear Ali, > > > > 1, -1, 0 are just spin indexes to tell the code what is the > relative > > magnetization of the atoms (parallel, antiparallel, or none). if > > your system is non magnetic put all 0. or set magn = .false. > and put > > nothing. > > you should look at the examples on Fe and Si as well and > learn from > > there by comparison. > > > > Matteo > > > > > > > > > -- > %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% > Matteo Cococcioni > Department of Chemical Engineering and Materials Science, > University of Minnesota > 421 Washington Av. SE > Minneapolis, MN 55455 > Tel. +1 612 624 9056 Fax +1 612 626 7246 > %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org </mc/compose?to=Pw_forum at pwscf.org> > http://www.democritos.it/mailman/listinfo/pw_forum > > > ------------------------------------------------------------------------ > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum > -- %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% Matteo Cococcioni Department of Chemical Engineering and Materials Science, University of Minnesota 421 Washington Av. SE Minneapolis, MN 55455 Tel. +1 612 624 9056 Fax +1 612 626 7246 %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%