Quantum Theory of Dissociative Chemisorption on Metal Surfaces

Recent theoretical progress in gas-surface reaction dynamics, a field relevant to heterogeneous catalysis, is described. One of the most fundamental reactions, the dissociative chemisorption of H2 on metal surfaces, can now be treated accurately using quantum mechanics. Density functional theory is used to compute the molecule-surface interaction, and the motion of the hydrogen atoms is simulated using quantum dynamics, modeling all six molecular degrees of freedom. Theory is in good quantitative agreement with molecular beam experiments, offering useful interpretations, and allowing reliable predictions. The success of the approach calls for extensions to larger systems, such as dissociative chemisorption of polyatomic molecules. Reactions at surfaces often correspond to rather complicated multistep processes, which hampers their theoretical modeling. For improved understanding of the overall reaction, a bottom-up approach has frequently been employed, involving atomistic studies of elementary reaction steps at well-defined single crystal surfaces. This approach has recently resulted in some remarkable successes. One study combined atomistic experimental and theoretical methods to establish that at elevated oxygen pressures, CO can be oxidized on ruthenium in a mechanism in which CO reacts with oxygen incorporated in the oxidized ruthenium surface. 1 In another example, the Geert-Jan Kroes obtained his Ph.D. in chemistry in 1990 at the University of Amsterdam, The Netherlands. He currently works as a Assistant Professor in the theoretical chemistry group of Leiden University. His research interests are focused on the dynamics of reactions, both in the gas phase and at surfaces. Axel Gross obtained his Ph.D. in physics in 1993 at the Technical Universit