First-principles calculations for SrTiO3(1 0 0) surface structure

As a continuation of our recent ab initio calculations of SrTiO3(1 0 0) surface relaxation for the two different terminations (SrO and TiO2) [Phys. Rev. B 64 (2001) 23417], we analyze here their electronic structures (band structure, density of states, and the electronic density redistribution with emphasis on the covalency effects). We compare results of ab initio Hartree–Fock method with electron correlation corrections and density functional theory with different exchange-correlation functionals, including hybrid (B3PW, B3LYP) exchange techniques. Our results are also compared with previous ab initio plane-wave local density approximation calculations and experiments when available. Considerable increase of Ti–O chemical bond covalency nearby the surface and the gap reduction, especially for the TiO2 termination, are confirmed.