Molecular surface scattering dynamic theories

Experiments have also played a critical role in the development of potential energy surfaces and reaction dynamics. In the earliest days of quantum chemistry, experimentally determined thermal rate constants were available to test and improve dynamical theories. Much more detailed information can now be obtained by experimental measurement. Today experimentalists routinely use molecular beam and laser techniques to examine how reaction cross-sections depend upon collision energies, the states of the reactants and products, and scattering angles. 

Atomic/molecular scattering is the fraction of incident particles that do not trap or stick irreversibly on impact with the surface. However, in adiabatic dynamic theory, the scattering results from the same PES as that which causes bond making/breaking, so that a study of those that got away also gives complimentary information about the bond making/ breaking dynamics. 

This paper also provided much of the early stimulus for developing semiclassical and quantum mechanical theories of chemical reaction dynamics, which is a research field that continues to be active. In addition, this paper provided the foundation for molecular dynamics studies of chemical reactions in condensed phases, including applications to gas-surface scattering and bio-molecular simulation. 

This book describes the proceedings of a NATO Advanced Research Workshop held at CECAM, Orsay, France in June, 1983. The Workshop concentrated on a critical examination and discussion of the recent developments in the theory of chemical reaction dynamics, with particular emphasis on quantum theories. Several papers focus on exact theories for reactions. Exact calculations on three-dimensional reactions are very hard to perform, but the results are valuable in testing the accuracy of approximate theories which can be applied, with less expense, to a wider variety of reactions. Indeed, critical discussions of the merits and defects of approximate theories, such as sudden, distorted-wave, reduced dimensionality and transition-state methods, form a major part of the book. The theories developed for chemical reactions have found useful extensions into other areas of chemistry and physics. This is illustrated by papers describing topics such as photodissociation, electron-scattering, molecular vibrations and collision-induced dissociation. Furthermore, the important topic of how to treat potential energy surfaces in reaction dynamics calculations is also discussed. 

According to the molecular scattering theory, a particle incident to the surface has a certain probability for a certain amount to stay on the surface, and the rest is scattered back into the gas phase, a is an initial attaching probability and is a parameter to be determined through a molecular dynamics simulation based on quantum chemistry. Although in surface chemistry, a thermal accommodation coefficient is also used, in atmospheric chemistry a mass accommodation coefficient is solely used so that here it is simply called an accommodation coefficient. In general a cannot be determined directly by experiments, and the experimentally determined parameter of intake of a gaseous molecule to the particle surface is an uptake coefficient y defined by... 

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