Condensed-phase system quantum overview

In chapter 1, Profs. Cramer and Truhlar provide an overview of the current status of continuum models of solvation. They examine available continuum models and computational techniques implementing such models for both electrostatic and non-electrostatic components of the free energy of solvation. They then consider a number of case studies with particular focus on the prediction of heterocyclic tautomeric equilibria. In the discussion of the latter they focus attention on the subtleties of actual chemical systems and some of the danger in applying continuum models uncritically. They hope the reader will emerge with a balanced appreciation of the power and limitations of these methods. In the last section they offer a brief overview of methods to extend continuum solvation modeling to account for dynamic effects in spectroscopy and kinetics. Their conclusion is that there has been tremendous progress in the development and practical implementation of useful continuum models in the last five years. These techniques are now poised to allow quantum chemistry to have the same revolutionary impact on condensed-phase chemistry as the last 25 years have witnessed for gas-phase chemistry. 

We present an overview of variational transition state theory from the perspective of the dynamical formulation of the theory. This formulation provides a firm classical mechanical foundation for a quantitative theory of reaction rate constants, and it provides a sturdy framework for the consistent inclusion of corrections for quantum mechanical effects and the effects of condensed phases. A central construct of the theory is the dividing surface separating reaction and product regions of phase space. We focus on the robust nature of the method offered by the flexibility of the dividing surface, which allows the accurate treatment of a variety of systems from activated and barrierless reactions in the gas phase, reactions in rigid environments, and reactions in liquids and enzymes. 

Chemical dynamics is the link between the potential energy surface (PES) (or surfaces) and an observable chemical phenomena. In principle the PES comes from an ab initio quantum chemistry calculation (within the Born-Oppenheimer approximation) though in practice it is often constructed by some more approximate model, e.g., semiempirical quantum chemistry or totally empirical force field models. First a brief overview of the present state of the methodology and scope of applications in this area is given. We will concentrate on chemical dynamics in the gas phase, though much of the methodology of this field has carried over to the study of dynamical processes in condensed phases, gas-surface collision processes, and also dynamics in biomolecular systems. 

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