High transmission in ruthenium-benzene-ruthenium molecular junctions

The conductance of a benzene molecule connected to two ruthenium (Ru) electrodes through two C(H) anchoring groups is investigated using a self-consistent ab initio approach that combines the non-equilibrium Green's function formalism with density functional theory. Our calculations demonstrate that a nearly perfect conductance with magnitude exceeding 84% of the conductance quantum G0 can be obtained when the two C(H) anchoring groups are bonded to a Ru adatom on the Ru(0 0 0 1) surface, independently from whether this is a RuC double bond or a RuC triple bond. Both the highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) of the benzene backbone interact with the Ru-C π bonds in the contact region to form efficient charge transport channels, illustrating the high conducting nature of benzene.