Six-dimensional quantum dynamics of dissociative chemisorption of H2 on metal surfaces

The implementation and application of six-dimensional (6D) quantum dynamical methods to the dissociative chemisorption of H2 on metal surfaces is reviewed. The validity of the approximations that are made in deriving the 6D model is discussed. Descriptions are provided of the 6D methods that have been developed, such as the coupled channel and two time-dependent wave-packet implementations. All quantum dynamics calculations were based on potential energy surfaces taken from density functional theory, using the generalized gradient approximation and a slab representation of the metal surface. The calculations yield trends concerning the influence of incidence energy, molecular vibration, angular momentum, alignment, and incidence angle on reactivity. Issues on which theory and experiment differ are laid bare, in some cases leading to suggestions for new experiments or calculations. The validity of classical mechanics for treating the dynamics is discussed, and areas in which further theoretical progress is needed are identified.