The new assignment of hyperfine parameters for deep defects in diamond

Hyperfine (hf) parameters calculated for the vacancy in diamond show deviations from the experimental data, that have been ascribed to the neglect of lattice relaxations. Extending the formalism to include lattice relaxations we have removed the discrepancies for the interactions with the nearest neighbor ligand nuclei. However, the disagreement for the interactions with the next neighbor shell apparently increased thereby. Extending our calculations to include all ligands up to the fifth shell we show that the hf interaction assigned to the next nearest neighbor shell at (2 2 0) must be reassigned to the (3 3 1) ligand shell instead. The same reassignment holds for substitutional Ni defects in diamond and for several deep donors in silicon, but apparently not for the silicon vacancy in SiC. (C) 2001 Elsevier Science B.V. All rights reserved.