Lattice dynamics of GaN: Effects of 3d electrons

We perform first-principles calculations of structural, dielectric, and 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 dielectric and vibrational properties are computed within the density-functional 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 bonding strength is determined, and their influence on the dielectric and dynamical properties of GaN is analyzed and discussed.