Thanks stefano and Burak. If space group matters, then the 3 types will be A, B and O.
On Tue, Jul 10, 2012 at 9:37 AM, Burak Himmetoglu <himm0013 at umn.edu> wrote: > Hi Peng, > > r.x assigns the values of the response matrices only by considering the > distance between atoms and whether they have the same spin and type or not. > This information has to be given by the user in the positions file > "filepos" read by &input_mat. If B(1) and B(2) are different types > (e.g. crystallographically) you should perturb them separately, as you > outlined in the procedure, and make sure that ntyp=3 (type 1 is B(1), type > 2 is B(2) and type 3 is O) in the namelist &input_mat that goes into r.x > > Best regards, > > Burak > > > On Tue, Jul 10, 2012 at 1:45 AM, Stefano de Gironcoli <degironc at > sissa.it>wrote: > >> I don't know the details of r.x code but I think that, physically, what >> matters is the two atoms are crystallographically equivalent or not >> .therefore I think space group symmetry is the relevant one. >> >> stefano >> >> >> On 07/10/2012 05:54 AM, Peng Chen wrote: >> >> Dear All, >> >> In the calculation of U, how can we determine the equivalence of the ions, >> by site symmetry or space group symmetry? >> E.g ABO3, B ions has 2 different site symmetries (B(1) B(2)). Shall we run >> calculation on perturbing B(1) and B(2) ions or just a B ion? >> >> In order to find U in B ions, I tried to run calculation with perturbing >> just on B, and r.x gave some errors that it needs to read more data. >> So I guess it needs the perturbed data from other atoms. Shall I use the >> procedures listed below? >> 1. run scf calculation with Hubbard_U(i)= 1.d-20 >> 2. run scf with perturbing on an A ion >> 3. run scf with perturbing on a B(1) ion >> 4. run scf with perturbing on a B(2) ion >> 5. run scf with perturbing on an O ion >> >> >> >> >> >> >> >> _______________________________________________ >> Pw_forum mailing listPw_forum at >> pwscf.orghttp://www.democritos.it/mailman/listinfo/pw_forum >> >> >> >> >> _______________________________________________ >> Pw_forum mailing list >> 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 > > -- Best Regards. Peng -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20120710/c8eb7a6a/attachment.htm
