Anomalous Enhancement of the p–d Hybridization in the σ-bonds of ABO₃ Perovskites Under the Lattice Expansion

Abstract

The first-principle calculations of the electric field gradient (EFG) on oxygen site for SrTiO₃ and BaTiO₃ as a function of cubic lattice parameter a show the increase of the absolute value of the EFG under the lattice expansion due to the decrease of the population of σ-orbitals. It means that the p–d hybridization in the σ-bonds increases with the increase of the bond length. We show that the non-trivial behavior is explained by the contribution of deep oxygen 2s states into the crystal field on Ti site.

Acknowledgment

We thank V.V. Laguta, K. Koch, and H. Rosner for valuable discussions and the PICS program (Contract No CNRS 4767, NASU 295) for support.