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The results of ab initio calculations of the structural, elastic, electronic, and phonon properties of BeO in both zinc-blende and wurtzite structures are presented. Our calculations are based on the application of plane-wave basis, pseudopotentials, and the generalized gradient approximation of the density functional scheme. Our total energy calculations indicate that the wurtzite phase has lower energy (around 5.8 meV) than zinc-blende phase. It is found that for the two crystal phases the values of the equilibrium atomic volume and of the bulk modulus and its pressure derivative are almost identical. The zinc-blende and wurtzite phases are predicted to be characterized with indirect (and smaller) and direct band gaps, respectively. The maximum longitudinal optical and transverse optical phonon frequencies in the zinc-blende phase compare well to the average of the corresponding E1 and A1 modes in the wurtzite phase.

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The electronic structures and elastic constants of LaSb and YSb are calculated using an ab initio pseudopotential scheme within the generalized gradient approximation. In agreement with experimental studies, it has been found that the upper valence bands in LaSb are characterized by Sb-5p and La-5d states. Our calculated elastic constants for LaSb are compared with available experimental data. A linear-response approach to density functional theory is used to derive phonon dispersion curves and the density of states for LaSb and YSb. Our phonon results for LaSb are in good agreement with experimental data. Frequency differences between phonon modes in these materials are discussed in terms of differences involving total mass, reduced mass and the lattice constant.