Electron Transport in Disordered Molecular Systems

这是由材料研究部和化学部共同资助的续期拨款。该理论项目侧重于无序在颗粒金属和导电聚合物的输运和自旋特性中的作用。颗粒金属的工作代表了这个正在进行的项目的新推动力。提出了杂质带和结垢的论点来解释实验观察到的颗粒金属的电导率。证明了颗粒金属的杂质带模型可以应用于导电聚合物聚苯胺。此外，用相互作用电子模型解释了聚苯胺的磁性能。将研究聚乙炔和结构紊乱对绝缘子-金属过渡的作用。最后，对高氯酸聚软鹿酯的二维动力学与一维动力学的交叉进行了研究。在真实的材料中，无序表现为原本完美的晶体或化学结构中的杂质或原子或分子的错位。这种无序会对材料的性能产生深远的影响。了解各种类型的无序及其对材料的影响是材料科学家面临的主要挑战。提出的研究将研究一种新的方法来研究无序对两种类型系统的影响：导电聚合物和颗粒金属。这两种材料都有重要的应用，并提出了巨大的理论困难。

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.