Six-dimensional quantum dynamics of dissociative chemisorption of H-2 on metal surfaces

The implementation and application of six-dimensional (6D) quantum dynamica l methods to the dissociative chemisorption of H-2 On metal surfaces is rev iewed. The validity of the approximations that are made in deriving the 6D model is discussed. Descriptions are provided of the 6D methods that have b een developed, such as the coupled channel and two time-dependent wave-pack et implementations. All quantum dynamics calculations were based on potenti al energy surfaces taken from density functional theory, using the generali zed 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 r eactivity. Issues on which theory and experiment differ are laid bare, in s ome cases leading to suggestions for new experiments or calculations. The v alidity of classical mechanics for treating the dynamics is discussed, and areas in which further theoretical progress is needed are identified. (C) 1 999 Elsevier Science Ltd. All rights reserved.