Vibrational properties of BaClF, BaBrF and BaIF under high pressure

Abstract

We have studied the Raman active optical phonons of layered BaClF, BaBrF and BaIF scintillators at ambient as well as at high pressures. The calculations were carried out using density functional perturbation theory within the local density approximation. We observed the softening of low and high frequency modes Eg(1) and Eg(3) under pressure. The calculated optical dielectric and Born effective charge tensors are found to be isotropic even though the crystal structures are anisotropic.