Rates of Elementary Mono- and Bimolecular Stages in a Non-Ideal Reaction System, Allowing for Indirect Correlations in the Cluster Variation Model

Equations for the rates of elementary mono- and bimolecular stages for non-ideal reaction systems are derived within the theory of absolute reaction rates in the cluster variation model (CVM). The theory allows for the difference between the interaction of particles in the ground and activated (transition) states. Locally equilibrium distributions of particles are calculated in a CVM that considers the influence of indirect correlations, making it possible to go beyond the limits of the quasichemic approximation, which reflects only the effects of direct correlations between interacting particles. The rates refer to the elementary stages of adsorption and desorption with and without allowing for the dissociation of molecules on a homogeneous flat face (100), along with the rate of the thermal motion of molecular jumps to neighboring vacant sites. The condition of self consistency in describing the rates of elementary stages and the equilibrium state of the system is confirmed in CVM approximations, starting from the basic 2 × 2 square cluster used to approximate the probabilities of obtaining reaction clusters of mono- and bimolecular stages with sizes K1 and K2. The principle of approximating the calculation of multiparticle probabilities of sizes K1 and K2 in terms of the probabilities of smaller basic clusters is discussed.