The passage of a system from one minimum energy state to another via a potential energy barrier provides a model for the microscopic description of a wide range of physical, chemical and biological phenomena. Examples include diffusion of atoms in solids or on surfaces, flux transitions in superconducting quantum interference devices (SQUIDs), isomerization reactions in solution, electron transfer processes, and ligand binding in proteins. In general, both tunneling and thermally activated barrier crossing may be involved in determining the rate. This book surveys key experiments chosen from physics, chemistry and biology, and describes theoretical methods appropriate for both classical and quantum barrier crossing. A major feature of the book is the attempt to integrate the experimental and theoretical work in one volume.Contents: Introduction (P Hänggi & G R Fleming)Variational Transition State Theory for Dissipative Systems (E Pollak)Multidimensional Barrier Crossing (A Nitzan & Z Schuss)Theoretical and Numerical Methods in Rate Theory (B J Berne)Barrier Crossing Phenomena in the Heme Pocket of Myoglobin (H Frauenfelder et al.)Friction Effects and Barrier Crossing (M Cho et al.)Chemical Aspects of Solution Phase Reaction Dynamics (D Raftery et al.)Solvent Effects in the Dynamics of Dissociation, Recombination and Isomerization Reactions (J Schroeder & J Troe)Thermally Activated Barrier Crossings in Superconducting Quantum Interference Devices (S Han et al.)Barrier Crossing at Low Temperatures (P Hänggi)Dynamics of the Spin-Boson System (U Weiss & M Sassetti)Readership: Condensed matter physicists, physical chemists and biophysicists.Key Features:Contributors are practitioners and academics from leading institutions such as Citigroup, Lehmen Brothers, JP Morgan, University of Cambridge, Imperial College London and Stanford University