The Effect of Symmetry Lowering on the Dielectric Response of $BaZr{O}_3$

We use first-principles density functional theory calculations to investigate the dielectric response of BaZrO${}_3$ perovskite. A previous study [Arkbarzadeh {\em et al.} Phys. Rev. B {\bf 72}, 205104 (2005)] reported a disagreement between experimental and theoretical low temperature dielectric constant $ϵ$ for the high symmetry BaZrO${}_3$ structure. We show that a fully relaxed 40-atom BaZrO${}_3$ structure exhibits O${}_6$ 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.