Dear Davide, I read the post before. I guess we actually have two problems: the Fermi-contact term and dipole-dipole term. Regarding the Fermi contact term, can you send me the code you mentioned so that I give it a try? Also, I don't think that the core-relaxation would completely cancel the dipole-dipole term.
Regards, Jones On Wed, Dec 9, 2009 at 3:01 AM, Davide Ceresoli <ceresoli at mit.edu> wrote: > Jones Tsz-Kai Wan wrote: >> Dear pwscf users >> >> Does anyone here have experience on HF calculation using gipaw? >> >> I made extensive test on hyperfine tensor calculation using the gipaw >> code, and I couldn't get reasonable result except free hydrogen atom. >> For H atom, the Fermi contact term (A_s) obtained (~1480) is within >> 10% of published work [e.g. Van de Walle and Blochl, PRB 47, 4244 >> (1993)]. However, the results for Si is unreasonable. The Fermi >> contact is only ~ 1% of the published data, and the dipole term (A_p) >> is zero, which is impossible. >> >> Jones Wan >> >> Published result: >> A_s ~ 1400 for H, A_s ~ -4200 and A_p ~ -100 [Van de Walle, PRB 47, >> 4244 (1993)]. > Dear Jones Wan, > ? ? because in Si the spin-density comes from p orbitals. The exchange > potential generated by the p orbitals, polarizes slightly the 3s orbital, > strongly the 2s electrons, which are not included in the pseudopotential. > One has to perform the core-relaxation. For further details, see the > following post: > http://www.democritos.it/pipermail/pw_forum/2009-September/014475.html > > Davide > > _______________________________________________ > Pw_forum mailing list > Pw_forum at pwscf.org > http://www.democritos.it/mailman/listinfo/pw_forum