A STOCHASTIC APPROACH TO SURFACE-REACTIONS INCLUDING ENERGETIC INTERACTIONS .1. THEORY

A stochastic model to describe surface reaction systems is introduced. The reactions may include mono-and bimolecular steps (i.e. adsorption , desorption, reaction and diffusion steps). Furthermore, energetic in teractions between the adsorbed particles are allowed. The temporal ev olution of the system is described by master equations using the Marko vian behaviour of these systems. The resulting infinite chain of equat ions is truncated at a certain level by using an improved superpositio n approximation. The equations are solved in a small lattice region ex actly and their solution is connected to continuous functions which re present the behaviour of the system for large distances. We define a s tandard model which can be used to model various surface reaction syst ems in a unique manner. This gives the possibility for a better and ea sier comparison between different models.