Modulation of the electronic transport properties of carbon nanotubes with adsorbed molecules

Green's function method has been applied to study the transport properties of single-walled carbon nanotubes (SWCNTs) reacting with C6H4 (benzyne) molecules. The system Hamiltonian is based on a density-functional fight-binding (DFTB) approach, which allows treatment of systems comprising a large number of atoms. The nanotube is ideally subdivided into three parts: a finite section on which the benzyne molecules are adsorbed, sandwitched in between two semi-infinite contacts. The ballistic current flowing across the two contacts is monitored during a molecular dynamics simulation of the central section of the nanotube reacting with one or more C6H4 molecules. The steady state current along the nanotube with the adsorbed molecules is strongly reduced with respect to the current flowing along the unperturbed nanotube. However, the current reduction depends strongly on the orientation of the molecule with respect to the nanotube axis. This is due to the breaking of phase coherence of the transmitted wave. (C) 2003 Elsevier Science B.V. All fights reserved.