Effect of substituting of S for O: The sulfide perovskite BaZrS₃ Bainvestigated with density functional theory

We use first-principles density functional theory calculations to investigate the ground-state structure of sulfide perovskite BaZrS₃. The material has a lower band gap than its oxide analog BaZrO₃. Neither are ferroelectric in the ground state at 𝑇=0 K. We also examine the IR-active phonon contributions to the dielectric constant 𝜖 of BaZrS₃, which are then compared to those of BaZrO₃. The roles of atomic size, mass, and covalency are discussed with regard to band gap and dielectric response.