Local modes of vibration at the vacancy and vacancy models of defects in diamond

The carbon vacancy in diamond and many similar defects have strong electron correlation giving rise to molecular multiplet structures. Sophisticated electron-phonon interaction subsequently occurs at these defects giving rise to optical and other effects associated with a dynamic Jahn Teller interaction. Using ab-initio calculations the full vibrational spectrum of both the neutral and negatively charged vacancy are obtained. Calculated local modes are consistent with earlier interpretations of vacancy properties as based upon Group Theory. Modification of the vibration spectra by a heavy metal - here nickel - is also examined and implications for defect vacancy models briefly discussed.