Ab initio study of transport properties of an all-carbon molecular switch based on C20 molecule

Choosing closed-ended armchair (5, 5) single-wall carbon nanotubes (CCNTs) as electrodes, we have investigated the electron transport properties across a carbon molecular junction consisting of a C₂₀ molecule sandwiched between two semi-infinite carbon nanotubes. It is shown that the Landauer conductance of this carbon hybrid system can be tuned within several orders of magnitude not only by varying the tube-C₂₀ distance, but more importantly by changing the orientation of the C₂₀ molecule and rotating the C₂₀ molecule or one of the tubes around the symmetry axis of the system at fixed distances. This fact could make this all-carbon molecular system a possible candidate for a nano-electronic switching device. Moreover, our study also reveals that molecular configuration selection and structural relaxation would play an important role in the design of such devices.