A computational study was made of the N vacancy in the +3, +2 and +1 charge states in the metastable zincblende phase. The vacancy and its 4 nearest-neighbor Al ions were treated as a molecular cluster, embedded in an infinite classical shell-model crystal. Various ground-state properties, all of which were determinable by experiment, were calculated: total spin, nearest-neighbor displacement, electron spin density at nearest-neighbor nuclei and breathing-mode force constant. The question of disproportionation among the 3 charge states was also considered, and the optical excitation energies were evaluated.

The Nitrogen Vacancy in Aluminium Nitride. J.M.Vail, D.K.Chevrier, R.Pandey, M.A.Blanco: Journal of Physics - Condensed Matter, 2006, 18, 2125-35