Structural analysis of terbium monopnictides under high pressure

In this work, theoretically study of structural, elastic, and mechanical properties of Terbium monopnictides TbX (X = P, As) in NaCl-B1 and CsCl-B2 phases are investigated using IIPM model. This model consists of Columbic interaction, three body interaction, polarizability effect and overlapping repulsive interaction operative up to second nearest neighbor. TbP and TbAs compounds exhibit structural phase transition from B1 to B2 phase at 46.3 GPa and 16.1 GPa pressure, respectively. The calculated structural phase transition pressures, bulk modulus and second order elastic constants are presented. Elastic constants and their related parameters such as Poisson's ratio, Young modulus and Shear modulus were also calculated. We have also predicted the pressure variation of the elastic and bulk modulus for B1 structure. We have compared our results with the available experimental and theoretical data.