Phase transitions in BaTiO$_3$ from first principles

TL;DR

This paper introduces a first-principles method to model ferroelectric phase transitions in BaTiO₃, accurately predicting phase sequences and transition properties through Monte Carlo simulations.

Contribution

It develops a fully first-principles effective Hamiltonian approach for ferroelectric transitions in perovskites, validated by comparison with experimental data.

Findings

Accurate phase transition temperatures and sequences for BaTiO₃

Good agreement of calculated properties with experiments

Insights into the nature of phase transition mechanisms

Abstract

We develop a first-principles scheme to study ferroelectric phase transitions for perovskite compounds. We obtain an effective Hamiltonian which is fully specified by first-principles ultra-soft pseudopotential calculations. This approach is applied to BaTiO$_3$, and the resulting Hamiltonian is studied using Monte Carlo simulations. The calculated phase sequence, transition temperatures, latent heats, and spontaneous polarizations are all in good agreement with experiment. The order-disorder vs.\ displacive character of the transitions and the roles played by different interactions are discussed.