Surface relaxation of SrTiO3(001)

Surface X-ray diffraction has been used to examine the 300 K structure of SrTiO3(001)1×1 with a termination of 78% TiO and 22% SrO. The data indicate that a lateral ferroelectric distortion is absent on both terminations, consistent with a recent theoretical calculation. Although the negligible Ti atom relaxation found on the TiO termination is consistent with medium-energy ion scattering data, it differs from recent density functional theory calculations by 0.13 and 0.16 Å. In contrast, the Sr displacement towards the SrO surface of 0.22±0.07 Å is in good agreement with theory.