Interatomic potential optimization to determine phase transitions in PbTiO₃ based on phonon dispersion

Abstract

When exploring new ferroelectric materials computationally, it is necessary to consider the temperature dependence and physical properties of the structure. In the present study, we used a classical molecular dynamics simulation to investigate phase transitions during high-temperature annealing of KNbO₃. The results revealed that a supercell larger than 8 × 8 × 8 is required to reproduce the phase transitions clearly. We also attempted to establish a method for obtaining the interatomic potential for any alloy composition. For PbTiO₃, this was achieved using genetic algorithm fitting, and a phonon dispersion curve similar to that simulated by first-principles calculation was obtained.