Adsorption and Dissociation ofO2on Ag(110)

First principles calculations for the adsorption of ${\mathrm{O}}_2$ on Ag(110) are presented. We find a peroxolike chemisorbed state whose geometry, binding energy, and dissociation path agree well with experiment. A second, superoxolike state appears to be a strongly overbound description of the observed physisorbed state. Also, no barrier is found into the chemisorbed state from the gas phase. The cause of these apparent inconsistencies with experiment for larger molecule-surface separations is discussed.