Dr. Gregory Voth is supported by a grant from the Theoretical and Computational Chemistry Program to perform theoretical studies of quantum mechanical activated rate processes in complex systems. This work provides an important theoretical background for understanding the energetics of chemical reactions which occur in solution. Dr. Voth's research will be directed at developing a theory for the transmission coefficient which accounts for the additional tunneling and multidimensional dynamical effects which can influence the value of the quantum rate constant. The quantum rate theory will be applied to the study of proton transfer reactions in condensed phases and to thereby obtain a better understanding of the influence of solvent polarization free energetics, intramolecular motions, and isotopic substitution on the value of the rate constant. The theory will also be used to examine the fundamental role of nonlinearity in condensed phase quantum activated rate processes.