SrTiO3andBaTiO3revisited using the projector augmented wave method: Performance of hybrid and semilocal functionals

The structural, electronic, and phonon properties of the cubic and tetragonal phase of ${\text{SrTiO}}_{3}$ and ${\text{BaTiO}}_{3}$ are studied from ab initio. The calculations are performed in the projector augmented wave density-functional theory framework using the local density approximation, gradient corrected functionals, and hybrid functional as implemented in the Vienna ab initio simulation package. Due to the large variation of theoretical predictions for the frequency of the ${\ensuremath{\Gamma}}_{15}$ (TO1) zone-center phonon mode $(94i\ensuremath{-}64\text{ }{\text{cm}}^{\ensuremath{-}1})$ special attention is accorded to this particular mode and its volume dependence.