Spin-density study of the silicon divacancy

Abstract

The possible charge states of the silicon divacancy ${\mathrm{V}}_{2}$ are studied using the local spin-density pseudopotential method. The ionic coordinates are relaxed without any symmetry constraints. We obtain the formation and binding energies as well as the ionization levels from total-energy calculations and use them to discuss several experiments. We find using the 216-atom-site supercell that ${V}_{2}^{0}$ and ${V}_{2}^{\ensuremath{-}}$ have a ``mixed'' structure that includes both pairing and resonant-bond characters, ${V}_{2}^{0}$ being more of the pairing type and ${V}_{2}^{\ensuremath{-}}$ more of the resonant-bond type.