Theoretical study of carotene as a molecular wire

Carotenoid molecules have important photo-chemical properties and may serve as molecular wires in a molecular electronic circuit. We have theoretically studied the intrinsic conducting properties of sulfur-terminated carotene between gold contacts using local orbital density functional theory. The dependence of the tunneling decay parameter “β” on the degree of single–double bond alternation within the polyene backbone is determined from the polyene complex band-structure. The electron tunneling current–voltage characteristics is calculated using the Landauer–Büttiker formalism. The calculations are in qualitative agreement with experiments.