Potential energy surface polyatomic reactions

Truhlar, D. G. and Steckler, R. Potential energy surfaces for polyatomic reaction dynamics, Chem. Rev., 87(1987), 217-236... 

Chang, Y.-T. and Miller, W.H. (1990) An Empirical Valence Bond Model for Constructing Global Potential Energy Surfaces for Chemical Reactions of Polyatomic Molecular Systems, J. Phys. Chem. 94, 5884-5888. 

The chaperon M forms a weak complex with A in the first step and stabilizes the product by removing energy in the second step. The relative importance of the two mechanisms depends on the details of the potential energy surface of the system, namely, whether the reactants are radicals or polar and whether M is a noble gas atom or a polyatom. These types of reactions are of current theoretical and experimental interest. 

This paper reviews recent (and current) work in my research group which is aimed at developing practical methods for describing reaction dynamics in polyatomic systems in as ab initio a framework as possible. To overcome the dimensionality dilemma of polyatomic systems—i.e., the fact that the potential energy surface depends on 3N-6 internal coordinates for an N atom system—we have developed dynamical models based on the intrinsic reaction path", i.e., the steepest descent path which connects reactants and products through the transition state (i.e., saddle point) on the potential energy surface. ... 

THE REPRESENTATION AND USE OF POTENTIAL ENERGY SURFACES IN THE WIDE VICINITY OF A REACTION PATH FOR DYNAMICS CALCULATIONS ON POLYATOMIC REACTIONS... 

The Born-Oppenheimer adiabatic approximation represents one of the cornerstones of molecular physics and chemistry. The concept of adiabatic potential-energy surfaces, defined by the Born-Oppenheimer approximation, is fundamental to our thinking about molecular spectroscopy and chemical reaction djmamics. Many chemical processes can be rationalized in terms of the dynamics of the atomic nuclei on a single Born Oppenheimer potential-energy smface. Nonadiabatic processes, that is, chemical processes which involve nuclear djmamics on at least two coupled potential-energy surfaces and thus cannot be rationalized within the Born-Oppenheimer approximation, are nevertheless ubiquitous in chemistry, most notably in photochemistry and photobiology. Typical phenomena associated with a violation of the Born-Oppenheimer approximation are the radiationless relaxation of excited electronic states, photoinduced uni-molecular decay and isomerization processes of polyatomic molecules. 

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