The Advances in Chemical Physics series provides the chemical physics field with a forum for critical, authoritative evaluations of advances in every area of the discipline. This volume explores the following topics: * Thermodynamic Perturbation Theory for Associating Molecules * Path Integrals and Effective Potentials in the Study of Monatomic Fluids at Equilibrium * Sponteneous Symmetry Breaking in Matter Induced by Degeneracies and Pseudogeneracies * Mean-Field Electrostatics Beyond the Point-Charge Description * First Passage Processes in Cellular Biology * Theoretical Modeling of Vibrational Spectra and Proton Tunneling in Hydroen-Bonded Systems