Ab initio calculation of the lattice dynamics of the boron group-V compounds under high pressure

High-pressure effects on the lattice dynamics and dielectric properties of the BN, BP, BAs, BSb and BBi alloys have been carried out using the density-functional perturbation theory within the local density approximation. We study the variation of the optical phonon frequencies (omega(TO) and omega(LO)), the high-frequency dielectric coefficient (epsilon(infinity)) and the dynamic effective charge (Z*) with pressure. The omega(TO) and omega(LO) have a quadratic form with pressure for all boron compounds. The obtained epsilon(infinity) and Z* for BN, BP remain constant with pressure. However, for BAs, BSb and BBi, epsilon(infinity) and Z* have a quadratic form with pressure. Our results are in good agreement with the available experimental data for BN and BP and they allow prediction for BAs, BSb and BBi.