While secondary effects such as next-nearest neighbor interactions and lattice distortions 4,22-24 play a role, the present analysis suggests that local interactions between a defect atom and the surrounding host atoms (or, in the case of the vacancies, interactions amongst the host atoms surrounding the vacancy site) provide a sufficient explanation for the defect charge states in the defect formation energy diagram. It is worth noting however that the relative energy placement of the molecular orbital with respect to the band edges is contingent on the accuracy of the DFT-calculated defect formation energy diagram; for example, had the charge state of V Si been +4 instead of +2, we would interpret the chemistry of the defect as involving the depopulation of both the t 1u states and the a 1g state, which would imply that the a 1g state resides in the conduction band instead of the valence band (Figure ).