Adsorption of Ar atoms on the relaxed defect-free TiO2(110) surface -: art. no. 235421

The interaction of Ar atoms with the relaxed and defect-free TiO2(110) surface was investigated by means of density functional theory within the GGA/PW91 exchange-correlation functional. A periodic three-dimensional slab plus vacuum width was used to model both the clean and Ar covered rutile surface. The calculations predict an important interlayer relaxation of the clean oxide surface when compared with the bulk rutile structure. The computed interaction energies are very small when atomic argon is deposited above this surface as expected for a physisorbed state. It was found that Ar prefers to interact with low coordination sites as found experimentally and theoretically for rare gases adsorbed on transition metal surfaces. On the rutile surface, Ar adsorbs preferentially on fivefold coordinated Ti sites, with an adsorbate to substrate height similar to that found experimentally for the Ar/Ag(111) system, while the least favorable site for adsorption is atop protruding oxygen atoms. The computed interaction energy on the most favorable adsorption site is 42 meV, almost 1/2 to 1/3 of the experimental binding energies recently reported for Ar adsorption on Ag(111), Ni(111), Pd(111), and Pt(111) surfaces.