Parameter-free prediction of phase transition in PbTiO3 through combination of quantum mechanics and statistical mechanics

TL;DR

This paper introduces a parameter-free method combining quantum and statistical mechanics to predict the ferroelectric-paraelectric transition in PbTiO3, aligning well with experimental results without fitting parameters.

Contribution

It demonstrates that the zentropy theory can accurately predict phase transitions in ferroelectric materials using first-principles domain wall energies, eliminating the need for empirical fitting.

Findings

Accurate prediction of FE-PE transition in PbTiO3 without fitted parameters.

Identification of relevant configurations including domain walls.

Remarkable agreement with experimental transition temperatures.

Abstract

Thermodynamics of ferroelectric materials and their ferroelectric to paraelectric (FE-PE) transitions including those in PbTiO3 is commonly described by the phenomenological Landau theory and more recently by effective Hamiltonian and various potentials, all with model parameters fitted to experimental or theoretical data. Here we show that the zentropy theory, which considers the total entropy of a system as a weighted sum of entropies of configurations that the system may experience and the statistical entropy among the configurations, can predict the FE-PE transition without fitting parameters. For PbTiO3, the configurations are identified as the FE configurations with 90- or 180-degree domain walls in addition to the ground state of the FE configuration without domain wall. With the domain wall energies predicted from first-principles calculations based on the density functional theory in the literature as the only inputs, the FE-PE transition for PbTiO3 is predicted showing remarkable agreement with experiments, unveiling the microscopic fundamentals of the transition.