Lattice dynamics of GaN: Effects of3delectrons

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 3$d$ electrons for the bonding strength is determined, and their influence on the dielectric and dynamical properties of GaN is analyzed and discussed.