First-principles study of phonons and intrinsic dielectric response of Ba(Ni1/3Ta2/3)O3

Electronic structure, lattice dynamics, and static dielectric response of 1:2 ordered Ba(Ni1/3Ta2/3)O3 are studied using the density functional theory. We find that, at intermediate value of on-site Coulomb interaction, the nature of the band gap is a mixture of Mott–Hubbard and charge-transfer type. After an analysis of electronic structure, zone-center optical phonon frequencies and their contributions dielectric response are evaluated. The computed dielectric constant and optical phonon frequencies are found to be in excellent agreement with experiments. Contributions of the dominant IR-active phonons to intrinsic static dielectric response are also analyzed in detail.