Atomistic study of soft-mode dynamics in PbTiO3

Ferroelectric PbTiO3 occupies a special place among ferroelectric materials owing to its unique status as a prototype displacive ferroelectric. However, while PbTiO3 undoubtedly provides one of the best examples of displacive phase transitions, several experimental and theoretical findings seem to suggest a certain degree of order-disorder mechanism associated with the phase transition. While multiple efforts have been undertaken to better understand the nature of the phase transition in this classic ferroelectric, the subject still remains controversial. Here we develop a force field from first principles to study soft mode dynamics in PbTiO3 from an atomistic viewpoint. Our computations indicate the presence of order-disorder mechanism in the vicinity of the phase transition in this classic displacive ferroelectric.