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