HYDROGEN DISSOCIATION ON METAL-SURFACES - A MODEL SYSTEM FOR REACTIONS ON SURFACES

Reactions on surfaces play an important role in many technological app lications. Since these processes are often rather complex, one tries t o understand single steps of these complicated reactions by investigat ing simpler systems. In particular the hydrogen dissociation on surfac es serves as such a model system. There has been much progress in rece nt years in the theoretical description of reactions on surfaces by hi gh-dimensional dynamics simulations on potential energy surfaces which are derived from ab initio total energy calculations. In this brief r eview I will focus on the hydrogen dissociation on the clean and sulfu r-covered Pd(100) surface. These calculations established the importan ce of dynamical concepts such as the steering effect. Furthermore the electronic structure calculations allow the determination of the facto rs that determine the reactivity of a particular surface. This will be demonstrated for the poisoning of hydrogen dissociation by sulfur ads orption on the Pd(100) surface, In addition, quantum effects in the dy namics can be assessed by comparing the results of classical with quan tum dynamical calculations on the same potential energy surface.