First-principles calculations were made of possible excited electronic structures for the N-V center. Molecular-orbital basis states were constructed for a center of C3v symmetry, with 2 to 6 active electrons, which fully accounted for the spin symmetries of the wave functions and permitted predictions to be made of level structure degeneracies and splitting patterns under the action of several magnetic and non-magnetic interactions. Detailed predictions of the resultant 3 models, which took account of spin-orbit, spin-spin, strain and Jahn-Teller interactions, were provided.

A.Lenef, S.C.Rand: Physical Review B, 1996, 53[20], 13441-55