Professor Michael B. Hall at the Department of Chemistry, Texas A&M University is supported by a grant from the Theoretical and Computational Chemistry Program at NSF for ab initio theoretical studies of problems of current interest in inorganic and organometallic chemistry, especially homogeneous catalysis. The computational methods which are being used involve full-gradient geometry optimization techniques for both multiconfiguration self-consistent-field and configuration interaction wavefunctions. The applications being made often require calculations at the frontier of those possible and, if necessary, the existing methods are modified and enhanced so that these calculations can be performed. The work under this grant is focused on the study and the characterization of four fundamental steps in catalytic reactions: oxidative-addition; substitution; migratory-insertion; and atom transfer. The systems being studied include models for biologically and industrially important catalytic oxidation processes. The work supported by this grant will help to provide the understanding which will allow researchers to make qualitative chemical predictions, without the need for further calculations, related to reactions involved in biological and industrial processes. A major objective is the discovery and prediction of systematic trends in the structures and reactivity of inorganic and organometallic systems. In order to achieve these objectives the systems being studied theoretically by Professor Hall are chosen to be as close as possible to systems being studied by experimentalists.