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

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