REACTION-PATH FOR THE DISSOCIATIVE ADSORPTION OF HYDROGEN ON THE (100)SURFACES OF FACE-CENTERED-CUBIC TRANSITION-METALS

Detailed ab-initio local-density-functional studies of the potential-e nergy surfaces for the dissociative adsorption of hydrogen molecules o n the (100) surfaces of face-centered-cubic transition and noble metal s are presented. We show that the energetically most favorable reactio n path is determined by quantum-mechanical steering effects arising fr om the formation and modification of covalent metal-hydrogen bonds. Va riations of the local chemical reactivity with the filling of the d-ba nd are discussed at the example of rhodium, palladium and silver surfa ces.