Hyperfine parameters which were calculated for the vacancy showed deviations from experimental data. These were attributed to the neglect of lattice relaxation. Upon extending the formalism so as to include lattice relaxations, discrepancies in the interactions with nearest-neighbor ligand nuclei were removed. However, the disagreement for interactions with the next-nearest neighbor shell then appeared to increase. By extending the calculations so as to include all ligands up to the fifth-nearest shell, it was shown that the hyperfine interaction which had been attributed to the next-nearest neighbor shell at (220) had to be re-attributed to the (331) ligand shell instead. The same re-attribution held for substitutional Ni defects in diamond, but apparently not for the Si vacancy in SiC.

The New Assignment of Hyperfine Parameters for Deep Defects in Diamond. U.Gerstmann, H.Overhof: Physica B, 2001, 308-310, 561-4