First-principles techniques were used to study the isolated self-interstitial. It was noted that the attribution of the R2 electron paramagnetic resonance center to the self-interstitial had been questioned because of a small fine-structure term. A spin-spin interaction tensor, which resolved the problem, was calculated. The optical properties of I1 were also modelled and an inversion-doubling process was proposed which gave rise to the 0.006eV splitting of the ground and first excited states. The 1.685 and 1.859eV lines could then be understood as being transitions between states that were made up from the p-orbitals on the 3-fold coordinated C atoms. The calculated piezo-spectroscopic tensor also agreed with experimental data.

First Principles Study of the Self-Interstitial Detect in Diamond. J.P.Goss, R.Jones, T.D.Shaw, M.J.Rayson, P.R.Briddon: Physica Status Solidi A, 2001, 186[2], 215-20