Electronic structure of the zinc-blende and rocksalt phases of InSb

The electronic structure of InSb in the common zinc-blende-crystal phase and in a rocksalt-crystal phase (which is metastable at standard temperature and pressure) are investigated using a self-consistent pseudopotential formalism including relativistic effects. For the zinc-blende structure we find that a local $s-p$ potential for the valence electrons yields, in a self-consistent calculation for the solid, a charge density in excellent agreement with previous calculations employing empirical nonlocal potentials. Relativistic effects are found to be very important in order to obtain a good description of the band gap and overall bandwidth. For the rocksalt phase we obtain a metallic solid, in agreement with experiment, and observe (in comparison with the zinc-blende results) substantial changes in the valence-band density of states. These results are in very good agreement with the experimental x-ray-photoemission-spectroscopy studies of these two phases. Unlike the situation for the covalently bonded zinc-blende crystal, we obtain very large charge transfer from the cations to the anions (estimated to be $0.9e^{-}$) in the metallic rocksalt phase, which we speculate helps to stabilize the solid. Band-structure, densities-of-states, charge-density, and Fermi-surface results are presented.