Dynamics and polarization of group-III nitride lattices: A first-principles study

We present a comprehensive picture of dynamical and electrostatic propertie s of boron, aluminum, gallium, and indium nitride. Our investigations are b ased on first-principles calculations within the density-functional theory and the local-density approximation. Starting from a careful investigation of the structure of the wurtzite ana zinc-blende polytypes, important prope rties of the nitride lattices are studied. Among them are the dynamical cha rges and the spontaneous polarization field. The phonon dispersion relation s are presented for the four group-ill nitrides. Chemical trends are derive d and related to the different strengths of covalent and ionic bonding.