Theory of vibrationally coupled pairwise charge transfer in a linear conjugated molecular chain

A model describing the electron charge transfer along a linear conjugated molecular chain based on a double harmonic oscillator picture is presented. Qualitatively, the model predicts three temperature regions of distinct conductivity characteristics: semiconductor-like (low temperature, TR-A), metal-like (high temperature, TR-C) and a narrow transition temperature region (TR-B) between the above two. In ideal cases, where the π-bond transfer frequency ω, coincides with the antisymmetric normal model of vibration frequency, υ, a cooperative pairwise charge transfer (“covalon”) is expected to take place leading to an anomalously high conductivity.