Study of Phonons in CaSiO3 Perovskite at Lower Mantle Pressure

Abstract

CaSiO₃ perovskite is thought to comprise between 6 and 12 weight % of the lower half of the earth’s transition zone and lower mantle (depths between 500 and 2900 km). Its structure throughout this regime is generally assumed to be cubic because x-ray diffraction studies have found no detectable deviation from Pm3m symmetry. Theoretical studies based on ionic models, periodic Hartree-Fock, and pseudopotential calculations  have supported this picture. In this work, we are reporting the results of our theoretical investigation on the phonon properties of CaSiO₃ in its cubic phase by using lattice dynamical simulation method based on de Launey angular force (DAF) constant model to understand the role of phonon in this system. The calculated zone center phonon frequencies agree well with available results.