Interface Geometry and Molecular Junction Conductance:  Geometric Fluctuation and Stochastic Switching

Metal/molecule/metal transport junctions can transport charge in the elastic scattering (Landauer) regime if the injection gap is large and the molecule is relatively short. Stochastic switching and broad conduction peak distributions have been observed in such junctions. We examine the effect of altering interface geometry on transport, using density functional calculations. For most structures, variations in conductance of order 0−300% are found, but when an atomic wire of Au binds to the molecule, symmetry changes can modify currents by a factor of 103.