Degree of coherence of single-component molecular wires: Dependence on length, coupling strength, and dissipative medium

We present a simple formula for determining the degree of coherence of molecular wires in which a single type of molecular moieties are connected for efficient long-range quantum transport. Using the recently developed reduced trajectory space analysis in combination with the on-the-fly filtered propagator functional path integral formalism, the degree of coherence of molecular wires is quantified in terms of the coherence length, the number of strongly correlated molecular units. By performing simulations on various molecular wires, we found that there exists a simple and general formula for the coherence length as a function of the electronic coupling and the reorganization energy. More importantly, the formula is applicable to electronic as well as photonic transfer systems and, thus, allows straightforward and systematic prediction of the quantum transport mechanism on a quantitative basis.