Pressure-induced phase transition phenomena in NpSe and NpTe

A three-body interaction potential (TBIP) has been formulated by incorporating the effects of long-range coulomb interaction, three-body interaction and short-range repulsive interactions effective up to second neighbor ions. The three-body interactions arise from the electron-shell deformation when the nearest-neighbor overlaps. This TBIP has been employed for detailed studies of pressure-induced phase transition and high-pressure behavior of NpSe and NpTe. The model has yielded fairly good description of the cohesive energy, compressibility, molecular force constant, reststralhlen frequency and Debye temperature in case of these actinide monochalcogenides.