  The structural, vibrational, energetic and electronic properties of hydrogen
at the stoichiometric RuO2(110) termination are studied using density
functional theory. The oxide surface is found to stabilize both molecular and
dissociated H2. The most stable configuration in form of hydroxyl groups
(monohydrides) at the undercoordinated O^br surface anions is at low
temperatures accessed via a molecular state at the undercoordinated Ru^cus
atoms (dihydrogen) and a second precursor in form of a water-like species
(dihydride) at the O^br sites. This complex picture of the low-temperature
dissociation kinetics of H2 at RuO2(110) is in agreement with existing data
from high-resolution energy-loss spectroscopy and temperature programmed
desorption. Hydrogen adsorption at O^br sites increases the reactivity of the
neighboring Ru^cus sites, which are believed to be the active sites in
catalytic oxidation reactions.
