Molecular wires: Extended coupling and disorder effects

Molecular wires are studied with respect to disorder and to increased electronic connectivity. We find that, with increased connectivity, the tendency to exhibit sharp changes of the conductance with modifications of the bridge structure is reduced. We find that the conductance falls off exponentially with distance for injection energies below the bridge energy band, and shows quantum behavior (oscillatory with wire length) for injection in the band. With disorder, we find that the distribution of conductances is lognormal, the parameters of which depend on disorder and on connectivity.