Kinetic Phase Transition in A_2+2B_2→2B_2A Reaction System with Particle Diffusion

A lattice gas model is presented for the A2 ＋2B2 → 2B2A reaction system with particle diffusion in two dimensions. In the model, B2 dissociates in the random dimer-filling mechanism and A2 dissociates in the end-on dimer filling mechanism. A reactive window appears and the system exhibits a continuous phase transition from a reactive state to a ＂B ＋ vacancy＂ covered state with infinitely many absorbing states. When the diffusion of particle B is considered, there are only two absorbing states. It is found that the critical behavior of the continuous phase transition changes from the directed percolation （DP） class to the pair contact process with diffusion （PCPD） class.