The generalized gradient approximation of a density functional theory in LCAO basis was used to determine electronic structure of charged point defects in hexagonal GaN. Impurities of MgGa, ZnGa, SiN and CN (the most common dopants) were considered for charge states 0, ±1, -2. The vacancies of VGa and VN were considered for charge states 0 and 0, ±1, ±2, respectively. The defects in consideration were compared from the point of view of the one-electron states localization. All the calculations were performed for a super-cell containing 96 atoms. The divergence due to periodically repeated charges was eliminated by the use of a uniform background charge of an opposite sign.

Ab initio Calculations of Charged Point Defects in GaN. A.Gulans, R.A.Evarestov, I.Tale, C.C.Yang: Physica Status Solidi C, 2005, 2[1], 507-10