Electrical transport through oligophenylene molecules: A first-principles study of the length dependence

We have calculated charge transport properties of molecular wires from first principles. The wires are made of oligophenylene molecules of three different lengths, in contact with atomic scale Au electrodes. The current-voltage characteristics of the wires are found to be linear, but the small bias resistances increase exponentially with the wire length. These behaviors are in qualitative agreement with recent experimental data. Quantitatively, our calculated slope of the resistance-wire-length curve is the same as the experimental data, while values of current and resistance are at the same order of magnitude as the data.