SPATIALLY NONLOCAL FLUCTUATION THEORY OF RAPID CHEMICAL-REACTIONS

Using ideas from statistical nonequilibrium thermodynamics we develop a spatially nonlocal theory of the influence of diffusion on rapid che mical reactions. The new approach generalizes the hydrodynamic (local) theory by including elementary events that influence both diffusion a nd reaction on molecular length scales and eliminates problems in the local theory that occur at short times. Examples of the nonlocal appro ach are given for several reaction schemes, including a simple reversi ble reaction A + B reversible arrow C, and single species reactions of the form A + A --> products. For low densities, the present theory is equivalent to the usual Smoluchowski method. In this regime, an inter mediate version of the theory, including only nonlocal effects due to reaction, is compared to the full nonlocal theory and to the earlier h ydrodynamic level theory and is shown to produce results for the time dependence of the radial distribution function that are similar at low density to the full theory. The application of the new approach at hi gher densities and to lower dimensions is described briefly. (C) 1996 American Institute of Physics.