The possible charge states of the Si divacancy were studied by using the local spin-density pseudopotential method. The ionic coordinates were relaxed, with no symmetry constraints. The formation and binding energies, as well as the ionization levels, were deduced from total-energy calculations. It was found, using a 216-atom super-cell, that V20 and V2- had a so-called mixed structure that included both pairing and resonant-bond characteristics. The V20 possessed more of the pairing type characteristic and V2- possessed more of the resonant-bond type characteristic.

Spin-density study of the silicon divacancy M.Pesola, J.Von Boehm, S.Pöykkö, R.M.Nieminen: Physical Review B, 1998, 58[3], 1106-9