Ab initio prediction of structural phase-transition temperature of SrTiO₃ from finite-temperature phonon calculation

The cubic-to-tetragonal phase transition temperature Tc of SrTiO3 is predicted from first-principles anharmonic lattice dynamics simulation. By using the self-consistent phonon approach, we compute finite-temperature phonon dispersion of cubic and tetragonal SrTiO3. By comparing the Helmholtz free energies of the two phases calculated with anharmonic effects included, we obtain Tc ∼ 80 K, which is comparable with the experimental value of 105 K. In addition, we show that the nuclear quantum effect is significant for predicting Tc. Our approach is efficient and provides a convenient way of predicting the phase stability of solids including ceramics, where the conventional approach based on the harmonic approximation often breaks down.