Effect of symmetry lowering on the dielectric response of BaZrO₃

Abstract

We use first-principles density functional theory calculations to investigate the dielectric response of BaZrO₃ perovskite. A previous study [Akbarzadeh et al., Phys. Rev. B 72, 205104 (2005)] reported a disagreement between experimental and theoretical low temperature dielectric constant 𝜖 for the high symmetry BaZrO₃ structure. We show that a fully relaxed 40 atom BaZrO₃ structure exhibits O₆ octahedral tilting, and 𝜖 that agrees with experiment. The change in 𝜖 from high-symmetry to low-symmetry structure is due to increased phonon frequencies as well as decreased mode effective charges.