(520d) Isolated Catalyst Sites on Amorphous Supports: A Systematic Ab Initio Route to Structure-Property Relationships

Methods for modeling catalytic sites on amorphous supports lag far behind methods for modeling catalytic sites on metal surfaces, zeolites, and other crystalline materials. One typical strategy for amorphous supports uses cluster models with arbitrarily chosen constraints to model the rigid amorphous support environment, but arbitrarily chosen constraints arbitrarily influence catalyst site activity.  A common alternative strategy uses no constraints, but this results in catalytic sites with unrealistic flexibility.  We present the first algorithm that systematically generates appropriately constrained structural models of active sites.  The algorithm generates a family of structural models that span some key determinant of reactivity, e.g. an overall activation energy.   The algorithm is illustrated for an empirical valence bond model energy landscape and for an Mo/SiO2 olefin metathesis catalyst. We also present a statistical framework for interpreting kinetics in systems with quenched disorder.