Ab initio modeling of surface structure for SrTiO₃ perovskite crystals

We present and discuss the results of calculations of SrTiO₃ (100) surface relaxation and rumpling with two different terminations (SrO and TiO₂). These are based on ab initio Hartree-Fock method with electron correlation corrections and density functional theory calculations with different exchange-correlation functionals, including hybrid exchange techniques. Both approaches use the localized Gaussian-type basis set. All methods agree well on surface energies and on atomic displacements, as well as on considerable increase of covalency effects nearby the surface. More detailed experiments on surface rumpling and relaxation are necessary for further testing theoretical predictions.