9520700 Ziff This project concerns basic research on two fundamental problems of material systems: the percolation transition in random media and cooperativity in surface reactions, such as in heterogeneous catalysis. The work on percolation revolves around gaining a fundamental understanding of the quantity that gives the probability of crossing a system of linear dimension L from one conducting side to the other, with given boundary conditions on the other sides. The investigator will carry out studies in both two and three dimensions. The work on catalysis begins with the Ziff, Gulari, and Barshad model of CO oxidation. He will study this model near the first-order transition and spinodal points to determine the importance of surface effects and metastability for that transition. He will also consider models for the NO-CO reactions, involving for the first time multiple pathways for N reaction. This work will lead to a substantial advance in the understanding of the phenomena available to these out-of-equilibrium, driven, surface reaction systems, and help in developing models that have practical application to real catalytic systems. %%% This project concerns research on two fundamental problems of materials systems. The first involves percolation in random media. The project involves understanding the probability of crossing a system of a given size from one conducting side to the other. This work has applications to flow through porous media (such as oil extraction through the ground) and electrical conduction in random systems (relating to the electrical breakdown of materials). The second involves a model of CO oxidation, which the authored developed several years ago and which many other researchers have also studied. This model is practically important as the foundation of practical models for surface reactions, such as those that take place in an automotive catalytic converter. ***
