Configuration and conductance evolution of benzene-dithiol molecular junctions under elongation

Benzene-dithiol is a prototype molecular junction that exhibits a perplexing conductance behavior. Here we report density-functional total-energy and conductance calculations during a simulated elongation process, pulling the electrodes apart from an initial proximal distance, as in related experiments. We find that transformations between different elongation paths result in ranges of small and large conductances, fluctuations, and discontinuities. The obtained complex conformational and conductance evolution allows us to account for the experimental observations.