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 list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum -------------- next part -------------- An HTML attachment was scrubbed... URL: http://www.democritos.it/pipermail/pw_forum/attachments/20120710/0a5535ed/attachment.htm
