Calculations of atomic and electronic structure for (100) surfaces of SrTiO₃ perovskite

We present and discuss main results of the calculations for the surface relaxation and rumpling of SrTiO₃ surfaces with TiO₂ and SrO terminations using a wide variety of methods of modern computational physics and chemistry, including the shell model (SM) and ab initio methods based on Hartree-Fock (HF) and Density Functional Theory (DFT). The HF and DFT formalisms with different exchange-correlation functionals are implemented into Crystal-98 computer code using a Gaussian-type basis set. We demonstrate that a hybrid B3PW formalism gives the best results for the bulk SrTiO₃ properties. Results are compared with previous ab initio plane-wave LDA calculations and LEED experiments. Our calculations demonstrate an increase of the covalency effects between Ti and O atoms near the surface.