LATTICE-DYNAMICS OF GAN - EFFECTS OF 3D ELECTRONS

We perform first-principles calculations of structural, dielectric, an d lattice-dynamical properties of cubic GaN. The equilibrium structure is obtained using the plane-wave pseudopotential approach within the density-functional theory and local-density approximation. The dielect ric and vibrational properties are computed within the density-functio nal perturbation theory. The effect of the Ga 3d electrons is treated by taking into account the nonlinear core corrections for the exchange and correlation energy. The importance of 3d electrons for the bondin g strength is determined, and their influence on the dielectric and dy namical properties of GaN is analyzed and discussed.