Ab initio investigation in PbZrO3 antiferroelectric: structural and vibrational properties

Using first-principles calculations, we investigate the structural and vibrational properties of PbZrO3. Starting from the high-symmetry cubic perovskite phase, for which the phonon dispersion curves are reported to have many unstable branches, we identify some key intrinsic characteristics allowing the prediction of materials with the propensity of developing an antiferroelectric behavior. We confirm the key role that R antiferrodistortive modes play in condensing the observed antiferroelectric phase, via a cooperative bilinear coupling, and the nearest with the ferroelectric state. Our work shows that, given all their important potential wells none of the individual modes condensed deletes all other and that it is their coupling which plays a key role in the condensation of the ground state lead zirconate, and these couplings would explain why Pbam and R3c phases are close in energy for promoting the first-order transition.