Polytypism of GaAs, InP, InAs, and InSb: An ab initio study

A systematic study of ground state properties of cubic (3C) and hexagonal (6H, 4H, 2H) polytypes of normal (nonnitride) III-V compounds is reported using well-converged density-functional calculations within local density approximation, ab initio pseudopotentials, and projector-augmented wave method. Equilibrium results are obtained for lattice parameters, cohesive energies, and bulk moduli. Internal degrees of freedom, i.e., atomic relaxations, are taken into account. Trends with the hexagonality are discussed. Within the axial next-nearest-neighbor Ising (ANNNI) model driving forces of the polytypism as well as the stacking fault formation are derived. The results are compared with available experimental data.