It was recalled that it was known that the neutral Si vacancy in 3C-type material exhibited negligible Jahn-Teller distortion. This made it possible to study the energy sequence of various multiplets in a vacancy having genuine Td symmetry. Calculations which were performed by using the local spin density approximation gave a spin triplet as the ground state. However, the determination of the true ground state required the incorporation of configuration interactions. By using multi-configurational self-consistent field calculations, it was shown that the ground state of VSi0 was a spin singlet. The calculated energy difference (0.1eV) in favour of the singlet spin state was expected to permit experimental observation of the triplet state at high temperatures.

The Spin State of the Neutral Silicon Vacancy in 3C-SiC P.Deák, J.Miró, A.Gali, L.Udvardi, H.Overhof: Applied Physics Letters, 1999, 75[14], 2103-5