Localization in quasi-one-dimensional systems

Summary form only given. The conductance in a polymeric system of nearly macroscopic dimensions is calculated using the many-channel Buttiker-Landauer formula. The conductance is studied as a function of various types of irregularities including on-site disorder, disorder in the intrachain hopping caused by chain twisting and sp/sup3/ defects, and disorder due to variations in the interchain ordering. Calculations are performed on strictly linear systems, like trans-polyacetylene, as well as on chains build up totally or partially from cyclic monomers. From the results of these studies we are able to determine the most important factors that cause localization of the electronic wavefunctions in quasi-one-dimensional polymeric systems. A discussion about the extension of these results to curved graphitic structures is also included.