title: When Langmuir is too simple: H2 dissociation on Pd(111) at high coverage.
abstract: Recent experiments of H2 adsorption on Pd(111) [Nature (London) 422, 705 (2003)]] have questioned the classical Langmuir picture of second order adsorption kinetics at high surface coverage requiring pairs of empty sites for the dissociative chemisorption. Experiments find that at least three empty sites are needed. Through density functional theory, we find that H2 dissociation is favored on ensembles of sites that involve a Pd atom with no direct interaction with adsorbed hydrogen. Such active sites are formed by aggregation of at least 3 H-free sites revealing the complex structure of the "active sites."
authors.affiliation: Departament de Química Física and Centre especial de Recerca en Química Teòrica, Universitat de Barcelona and Parc Científic de Barcelona, Spain. n.lopez@qf.ub.es
authors.forename: Nuria
authors.initials: N
authors.lastname: Lopez
authors.forename: Zbigniew
authors.initials: Z
authors.lastname: Łodziana
authors.forename: Francesc
authors.initials: F
authors.lastname: Illas
authors.forename: Miquel
authors.initials: M
authors.lastname: Salmeron