ANNIHILATION REACTIONS IN 2-DIMENSIONAL PERCOLATION CLUSTERS - EFFECTS OF SHORT-RANGE INTERACTIONS

We report Monte Carlo simulations of annihilation reaction A + A --> 0 in two-dimensional percolation clusters. In the model, the particles diffuse coupled by nearest-neighbor (NN) and next-nearest-neighbor (NN N) interactions. The following cases have been studied: (i) repulsive NN interaction, (ii) repulsive NN and NNN interactions, and (iii) repu lsive NN and attractive NNN interactions. In the intermediate-time reg ime, for cases (i) and (ii), we found that the density of particles rh o approximately decays as rho approximately t(-gamma)(2/3 < gamma < 1) , where gamma depends on specific values of interactions but is indepe ndent of the initial density rho(t = 0). For case (iii) there is no po wer-law decay. For the short- and intermediate-time regimes, a scaling ansatz for cases (i) and (ii) is found.