This Presidential Young Investigator Award in the Theoretical and Computational Chemistry Program centers on the use of theoretical techniques to predict the chemical behavior of adsorbates on metal and semiconductor surfaces. A unique combination of both ab initio quantum chemistry methods, to determine the fundamental potential energies of interaction, and classical molecular dynamics methods, to simulate the progress of individual reaction steps, will be used to address these problems. The research will focus on such systems as (i) bare metal and main group clusters; (ii) atomic and molecular adsorbates on those clusters; (iii) catalytic reactions including oxidation and hydrogenation of hydrocarbons, ammonia synthesis and decomposition, and reduction of sulphur and nitrogen oxides; and (iv) synthesis of electronic materials via chemical vapor deposition, molecular beam epitaxy, and chemical etching. The ultimate goal of these studies is to learn how to predict optimal reaction conditions for development of new electronic materials and for the design of new catalysts.