Medium-energy ion-scattering study of the structure of clean TiO2(110)-(1x1)

100 keV H+ medium-energy ion scattering has been applied to investigate the surface relaxations of the clean rutile TiO2(110)-(1x1) surface structure. A set of blocking curves in four different incident directions show clear differences between the surface and bulk attributable to surface relaxation. Optimized values of the surface relaxation parameters to give the best fit to the surface structure are generally in quite good agreement with a recent experimental determination of this structure using quantitative low-energy electron diffraction. In particular, both solutions favor an outward relaxation of the bridging O atoms on the surface rather than the strong inward displacement favored by the only previous experimental structure determination based on surface x-ray diffraction.