Dr. Susan Tucker is supported by a grant from the Theoretical and Computational Chemistry Program to study supercritical fluid solvent effects on chemical reaction rates. Molecular dynamics and Monte Carlo simulations will be used to characterize the pressure and temperature dependence of both the static and dynamic components of the solvation effects. For both of these components, critical tests of theoretical methods against the simulation results will be used to determine the importance of behaviors which are unique to SCF solvents, such as clustering, and to identify which of these must be incorporated into theoretical models designed specifically to treat supercritical solvent effects. %%% Supercritical fluid solvents have proven to be an exciting medium for chemical reactions, both for the oxidative destruction of hazardous organics and for the selective synthesis of commodity chemicals. The uniqueness of supercritical fluid solvents arises because their solvating properties may be changed dramatically with only modest changes in pressure and temperature. The proposed theoretical studies will provide a significant advance in our molecular level understanding of these technologically important solvents.