Conductivity in alkali doped polyacetylene .5. Reorganization energy and interchain coupling induced by the alkali ion

The electronic structure of two ethene molecules and two allyl radicals in the presence of an alkali atom are studied using ab initio methods as a simplified model of electron transfer (ET) for an alkali-dopant site for ET in polyacetylene. At the optimized structure the systems are stable charge transfer complexes, where the charge is transferred to one of the monomers. Parameters of interest for the understanding of electron transfer steps in alkali doped polyacetylene, such as reorganization energy and electronic factor for ET, are calculated. We find for the two systems studied here an important additional contribution to the reorganization energy for ET between the chains (about 0.40 eV) due to the motion of the alkali ion. (C) 1996 American Institute of Physics.