First-principles study of electron transport through C 20 cages

Electron transport properties of ${\mathrm{C}}_{20}$ molecules suspended between gold electrodes are investigated using first-principles calculations. Our study reveals that the conductances are quite sensitive to the number of ${\mathrm{C}}_{20}$ molecules between electrodes: the conductances of ${\mathrm{C}}_{20}$ monomers are near ${1G}_{0},$ while those of dimers are markedly smaller, since incident electrons easily pass the ${\mathrm{C}}_{20}$ molecules and are predominantly scattered at the ${\mathrm{C}}_{20}\ensuremath{-}{\mathrm{C}}_{20}$ junctions. Moreover, we find both channel currents locally circulating the outermost carbon atoms.