Accurate Modeling of the Cubic and Antiferrodistortive Phases of SrTiO3 with Screened Hybrid Density Functional Theory

TL;DR

This study evaluates various density functionals for modeling SrTiO3's cubic and antiferrodistortive phases, demonstrating that screened hybrid functionals with large basis sets yield highly accurate structural and electronic predictions.

Contribution

It provides the most accurate computational modeling of SrTiO3's phases to date using screened hybrid density functionals combined with large basis sets.

Findings

Screened hybrid functionals predict structural properties in excellent agreement with experiments.

Large basis sets improve the accuracy of phase property predictions.

HSE06/modified-def2-TZVP offers the most precise modeling of SrTiO3's phases.

Abstract

We have calculated the properties of SrTiO3 (STO) using a wide array of density functionals ranging from standard semi-local functionals to modern range-separated hybrids, combined with several basis sets of varying size/quality. We show how these combination's predictive ability varies significantly, both for STO's cubic and antiferrodistortive (AFD) phases, with the greatest variation in functional/basis set efficacy seen in modeling the AFD phase. The screened hybrid functionals we utilized predict the structural properties of both phases in very good agreement with experiment, especially if used with large (but still computationally tractable) basis sets. The most accurate results presented in this study, namely those from HSE06/modified-def2-TZVP, stand as the most accurate modeling of STO to date when compared to the literature; these results agree well with experimental structural and electronic properties as well as providing insight into the band structure alteration during the phase transition.