Current-voltage curves for molecular junctions: the effect of Cl substituents and basis set composition

Current-voltage characteristics of gold-benzene-1,4-dithiol-gold junctions are calculated using a combined density functional theory/non-equilibrium Green's functions approach with local atomic basis sets. Improving the basis set with the addition of polarization or diffuse functions has some effect on the computed I-V curves, but even the small valence double zeta sets yield reasonable results. The results obtained using the hybrid B3LYP functional give slightly smaller conductance than those obtained using the pure BPW91 approach. Substituting Cl for H on the bridging molecule has only a small effect on the I-V curves. (C) 2004 Elsevier B.V. All rights reserved.