Experimentally identified deep levels inp-type GaN at approximately 0.9–1, 1.4, and 1.8–2 eV above the valence-band maximum have been attributed to Ga vacancies. From the results of first-principles calculations, we find that from both energetic and electronic level structure standpoints it is necessary to consider the structural modificationVGa→Nanti+VN,resulting from the transfer of a nearest-neighbor N atom to a Ga-vacancy site(VGa)to explain the levels at 1 and 2 eV. Isolated N-antisite(Nanti)and nitrogen-vacancy(VN)defects are found to give rise to additional deep levels at 1.4 and 0.8 eV, respectively. ©1997 American Institute of Physics.