A Set of Interaction Potentials for Molecular Dynamics Simulations of YPO4 Crystal

A set of empirical pair interaction potentials for molecular dynamics (MD) modeling of the YPO4 crystal is proposed. The parameters of the potentials, as well as the effective charges of the ions, are recovered based on experimental data on the lattice constants of YPO4, as well as on the structure of the PO4 complex within this crystal. Using these potentials, an MD simulation of YPO4 crystallites isolated in vacuum is performed in the temperature range from 300 K to 2200 K. A quantitative agreement between the thermal expansion coefficient of the crystal and experimental data is obtained. Simulation of the formation of Frenkel defects in the yttrium, oxygen, and phosphorus sublattices is carried out. The formation energy of the Frenkel defects in the oxygen and yttrium sublattices is in quantitative agreement with ab initio calculations.