Elastic constants and electronic structure of beryllium chalcogenides BeS, BeSe, and BeTefrom first-principles calculations

We use an ab initio total energy pseudopotential technique within the local-density aproximation to determine the full set of first-order elastic constants of BeS, BeSe, and BeTe, which have not been established experimentally. For BeS we obtain ${\mathrm{C}}_{11}$=1.84, ${\mathrm{C}}_{12}$=0.75, and ${\mathrm{C}}_{44}$=0.99 Mbar. For BeSe and BeTe we obtain ${\mathrm{C}}_{11}$=1.49, 1.11; ${\mathrm{C}}_{12}$=0.59, 0.43; and ${\mathrm{C}}_{44}$=0.81, 0.60 Mbar, respectively. We also calculate the bulk modulus, the optical phonon frequency at Γ, and we present a study of the electronic band structure of those compounds. The calculated bulk moduli agree well with previous experimental and theoretical values.