Challenges in predictive calculations of processes at surfaces: surface thermodynamics and catalytic reactions

Obtaining a predictive description of reaction processes at surfaces is one of the goals and challenges of modern theoretical surface science. Over th e last few years significant advances have been made in this direction due to increased computer power and methodological developments. In the present paper we describe some recent progress. As a specific example, we discuss our first-principles-based approach for the thermodynamics and kinetics of adparticles at surfaces, which is applied to the system of oxygen at ruthen ium, For the same system, we also describe some results of our investigatio ns into the oxidation of CO and the formation of subsurface oxygen species.