First-principles calculations of structural properties of GaN : V

Using first-principles calculations, by means of The Full-Potential Linearized Augmented Plane Wave (FP-LAPW) method with the Gradient Generalized Approximation (GGA), we have investigated the main structural characteristics of Ga1−xV xN (with x=0;0.25;0.50;0.75;1. The study was carried out in the structures wurtzite and rocksalt because the former is the most stable structure of the GaN, whereas the latter is the most stable structure of the VN. In order to determine the best parameters in the wurtzite structure, the total energy was optimized in function of: (i) the volume of the unit cell, (ii) the relation c/a and (iii) the internal parameter u. For the rocksalt structure the energy was optimized in function of unit cell volume only. As a result we have found that the lattice constant approximately follows Vegard's law. We have also observed that for vanadium (V) concentrations less than 75%, the most favorable structure is wurtzite. However, for concentrations larger than 75% of vanadium, the most stable structure is the rocksalt.