AbstractThe molecular dynamics simulation method is extended to study a model of diffusion-controlled reactions. This allows a molecular description of a solvent at an equal footing of reactants. The dynamics of a solvent and its local structure significantly affect the dynamics of reacting species in the short time region. In this region, the rate of the migration of reactants is much larger than that given by Smoluchowski’s theory. The simulation results establish that Smoluchowski’s theory describes correctly the long time asymptotic behaviour of the time-dependent rate coefficient.