The 2×1 Reconstruction Of The Rutile Tio_2(011) Surface: A Combined Density Functional Theory, X-ray Diffraction, And Scanning Tunneling Microscopy Study

摘要

An extensive search for possible structural models of the (2 × 1 )-reconstructed rutile TiO_2(011) surface was carried out by means of density functional theory (DFT) 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 (SXRD) and voltage-dependent STM measurements. The model that is (by far) energetically most stable shows also the best agreement with SXRD data. Calculated STM images agree with the experimental ones for appropriate tunneling conditions. In contrast to previously-proposed models, this structure is not of missing-row type; because of its similarity to the fully optimized brookite TiO_2(001) surface, we call it the 'brookite(001)-like' model. The new surface structure exhibits two different types of undercoordinated oxygen and titanium atoms, and is, in its stoichiometric form, predicted to be rather inert towards the adsorption of probe molecules.