This is a renewal grant jointly funded by the Divisions of Materials Research and Chemistry. The theoretical project focuses on the role of disorder on the transport and spin properties of granular metals and conducting polymers. The work on granular metals represents a new thrust to this ongoing project. Impurity band and scaling arguments are proposed to explain the experimentally observed conductivity in granular metals. It is shown how the impurity band model for granular metals can be applied to conducting polymer polyaniline. In addition, an interacting electron model is used to explain the magnetic properties of polyaniline. Studies will be conducted on polyacetylene and the role of structural disorder on the insulator- metal transition. Finally, a study of the crossover from two- to one-dimensional dynamics in the polymer poly-pyrolle perchlorate will be undertaken. %%% In real materials disorder manifests itself through impurities or the misplacement of atoms or molecules in an otherwise perfect crystal or chemical structure. This disorder can have profound effects on the properties of materials. The understanding of various types of disorder and its influence on materials represents a major challenge to materials scientists. The proposed research will study a novel approach to the effects of disorder on two types of systems: conducting polymers and granular metals. Both of these materials have important applications and pose formidable theoretical difficulties.
