Electron transfer in poly( p-phenylene) oligomers: effect of external electric field and application of Koopmans theorem

Abstract

For the purpose of investigating the interchain electron transfer mechanism in poly( p-phenylene) (PPP), intermolecular electron transfer (ET) reactions between the parallel benzene cation radical and neutral benzene have been studied at the levels of 4-31G and DZP basis sets. The dependence of the ET matrix element V rp upon d, the distance between the two parallel donor and acceptor, has been elucidated. Considering the motion of charge carrier in external electric field, we have studied the influence of the uniform electric field on the electron transfer matrix element and the location of the avoided crossing. We have found that the one-electron Koopmans theorem can be applied to the estimation of the electron transfer matrix element, and that the position of the avoided crossing can be determined by pursuing the minimum MO energy-splitting factor. Conformations of PPP oligomers, up to 10 phenyl rings, have been optimized with AM1 semiempirical method. The torsion angle between two vicinity phenyl rings, and the ionization potential have been calculated and discussed.