GaN Xu Y N, Ching W Y Physical Review B48 (1993) 4335-4351 Electronic, optical, and structural properties of some wurtzite crystals _database_code_amcsd 0015172 3.190 3.190 5.189 90 90 120 P6_3mc atom x y z Ga 2/3 1/3 0 N 2/3 1/3 .375