  The properties of neutral defects in SrTiO3 are calculated using the screened
hybrid density functional of Heyd, Scuseria, and Ernzerhof. The formation
energies, the crystal field splittings affecting the SrTiO3 band structure, and
the relaxation geometries around each defect are discussed. Oxygen vacancies
introduced in SrTiO3 are found to cause a small tetragonal elongation of the
lattice along the z-axis. The resulting conduction band minimum electron
effective masses deviate from the bulk values and support the proposal of
enhanced electron mobility along the direction of the compressive strain. The
locations of the various defect bands within the SrTiO3 gap are estimated
without introducing any post hoc corrections, thus allowing a more reliable
comparison with experiment.
