Mixed Dissociative and Molecular Adsorption of Water on the Rutile (110) Surface

Using first-principles density-functional methods we show that a monolayer of water on the rutile (110) surface contains ${\mathrm{H}}_2\mathrm{O}$ in both molecular and dissociated forms. Intermolecular hydrogen bonding stabilizes this configuration with respect to the complete dissociative adsorption which would be predicted from studies at lower coverage. The proposed mixed adsorption mode is fully consistent with experimental data, reconciles apparent conflicts within these data, and explains discrepancies between experiment and previous calculations.