Modeling of the cubic and antiferrodistortive phases of SrTiO₃ with screened hybrid density functional theory

We have calculated the properties of SrTiO₃ (STO) using a wide array of density functionals ranging from standard semilocal functionals to modern range-separated hybrids, combined with several basis sets of varying size and quality. We show how these combinations' predictive ability varies significantly, for both STO's cubic and antiferrodistortive (AFD) phases, with the greatest variation in functional and 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 with a modified def2-TZVP basis set, stand as one of the most accurate modelings 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.