The Number of Transmission Channels Through a Single-Molecule Junction

We calculate transmission eigenvalue distributions for Pt−benzene−Pt and Pt−butadiene−Pt junctions using realistic state-of-the-art many-body techniques. An effective field theory of interacting π-electrons is used to include screening and van der Waals interactions with the metal electrodes. We find that the number of dominant transmission channels in a molecular junction is equal to the degeneracy of the molecular orbital closest to the metal Fermi level.