Monte-Carlo studies on three-species two-particle diffusion-limited reactions

We studied two models of three-species two-particle diffusion-limited reactions with and without a drift. Model A involves annihilations A+B → 0, B+C → 0, and C+A → 0 with hard-core interactions between like species, and assumes equal initial densities of the species. The density decays according to a power law, C(t) t−α. The critical exponent was estimated as α = 0.353(6) without the drift and α = 0.390(4) with the maximum drift. Model B is a coagulation model as A+B → C, B+C → A, and C+A → B. In this model we observed the critical exponent regardless of the drift. We argue that model B belongs to the same universality class as single species annihilation or coagulation diffusion limited reactions. We also studied the average distance of the nearest-neighbor species, the average domain size, and the average number of the species pairs.