An extensive search for possible structural models of the (2 x 1)-reconstructed rutile TiO2(011) surface was carried out by means of density functional theory calculations. A number of models were identified that have much lower surface energies than the previously-proposed ‘titanyl’ and ‘microfaceting’ models. These new structures were tested with surface X-ray diffraction and voltage-dependent scanning tunnelling microscopy measurements. The model that was (by far) energetically most stable showed also the best agreement with surface X-ray diffraction data. Calculated scanning tunnelling microscopic images agree with the experimental ones for appropriate tunnelling conditions. In contrast to previously-proposed models, this structure was not of missing-row type. Because of its similarity to a fully optimized brookite TiO2(001) surface, it was termed a brookite (001)-like model. The new surface structure exhibited two different types of under-coordinated oxygen and titanium atoms, and is, in its stoichiometric form, predicted to be rather inert towards the adsorption of probe molecules.

The 2 x 1 Reconstruction of the Rutile TiO2(011) Surface - a Combined Density Functional Theory, X-Ray Diffraction, and Scanning Tunnelling Microscopy Study. Gong, X.Q., Khorshidi, N., Stierle, A., Vonk, V., Ellinger, C., Dosch, H., Cheng, H., Selloni, A., He, Y., Dulub, O., Diebold, U.: Surface Science, 2009, 603[1], 138-44