Influence of exchange and correlation on structural and electronic properties of AlN, GaN, and InN polytypes

Results for structural and elastic properties of wurtzite and zinc-blende group-III nitrides are calculated using the recently developed AM05 exchange-correlation (XC) functional. They are compared to calculations based on the local-density approximation or the generalized-gradient approximation. We find that AM05 provides a better agreement with experimental results. The atomic geometries are used to compute the quasiparticle band structures within Hedin's GW approximation, based on an initial electronic structure calculated using the HSE hybrid XC functional. Important band parameters such as gap energies, crystal-field splittings, spin-orbit coupling constants, and momentum matrix elements are derived. The less precisely known hole masses of InN and the anisotropic spin-orbit constants for wurtzite are predicted. The wave-vector-induced spin-orbit splittings of the valence and conduction bands are discussed.