Nonequilibrium liquid state molecular theory

Kirkwood and co-workers 4-47> 35>36 have more recently presented molecular theories of transport processes in liquids making use of extensions of nonequilibrium statistical mechanics which were developed for the purpose. The assumed structure of the liquid state was quite general with the principal restriction that it be composed of spherical molecules. Some further simplifying assumptions were introduced at later stages in the treatments in order to render the mathematical derivations tractable. 

With the intensive development of ultrafast spectroscopic methods, reaction dynamics can be investigated at the subpicosecond time scale. Femtosecond spectroscopy of liquids and solutions allows the study of sol-vent-cage effects on elementary charge-transfer processes. Recent work on ultrafast electron-transfer channels in aqueous ionic solutions is presented (electron-atom or electron-ion radical pairs, early geminate recombination, and concerted electron-proton transfer) and discussed in the framework of quantum theories on nonequilibrium electronic states. These advances permit us to understand how the statistical density fluctuations of a molecular solvent can assist or impede elementary electron-transfer processes in liquids and solutions. 

The study of liquid-state dynamics is an important branch of nonequilibrium statistical physics. Over the past 40 years this active field of research has seen new and important developments. These developments, however, are largely limited to a system of spherical particles, and are not directly applicable to the description of dynamics of molecular systems. Nonetheless, ideas and concepts acquired during the growth of a modern theory constitute the bases in constructing molecular-liquid theories, and in the following main features of those developments for simple liquids are briefly surveyed. 

Ray Kapral came to Toronto from the United States in 1969. His research interests center on theories of rate processes both in systems close to equilibrium, where the goal is the development of a microscopic theory of condensed phase reaction rates,89 and in systems far from chemical equilibrium, where descriptions of the complex spatial and temporal reactive dynamics that these systems exhibit have been developed.90 He and his collaborators have carried out research on the dynamics of phase transitions and critical phenomena, the dynamics of colloidal suspensions, the kinetic theory of chemical reactions in liquids, nonequilibrium statistical mechanics of liquids and mode coupling theory, mechanisms for the onset of chaos in nonlinear dynamical systems, the stochastic theory of chemical rate processes, studies of pattern formation in chemically reacting systems, and the development of molecular dynamics simulation methods for activated chemical rate processes. His recent research activities center on the theory of quantum and classical rate processes in the condensed phase91 and in clusters, and studies of chemical waves and patterns in reacting systems at both the macroscopic and mesoscopic levels. 

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