Structural relaxation and longitudinal dipole moment of SrTiO3(001)(1X1) surfaces

First-principles calculations are employed to study SrTiO3(001) (1x1) surfaces with both SrO and TiO2 termination. A detailed geometry of the relaxed systems, surface energy, and the individual relaxation energies of the two types of surface are obtained. The longitudinal surface dipole moments are derived from variation of the macroscopic electrostatic potential along the surface normal direction. Pseudopotential-plane-wave calculations are performed in the slab geometry, on both symmetric and;asymmetric slabs; the merits and the limits of the latter geometry are discussed.