A Difiusion-Limited Reaction

Fluctuations in difiusion-controlled reactions lack the necessary fea- tures for a mesoscopic description. We show how the correlations dominate the dynamics by juxtaposing the macroscopic dynamics of a cellular automaton model for the difiusion-controlled limit to the deterministic difiusion-reaction rate equation for the same reaction. A more detailed N-body master equation is then presented in which explicit difiusion-controlled limits are explained.