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Molecular-Dynamics Study Of Phase Transitions In Alkali Azides, M. M. Ossowski, John R. Hardy, Robert W. Smith

Physics Faculty Publications

An account is presented of our studies of the order-disorder phase transitions in KN₃, RbN₃, and CsN₃. These are based on parameter-free interionic potentials based on the Gordon-Kim modified electron-gas formalism extended to molecular ions. We performed static structural relaxations and supercell molecular dynamics and predicted with reasonable accuracy the temperatures for the onset of the transitions. In particular, we address the question of how the N₃^- ions reorient to yield the transitions. We found the existence of NaCl-type high-temperature phases in disordered KN₃ and RbN₃ and argue that this …