Dynamic Current Suppression and Gate Voltage Response in Metal-Molecule-Metal Junctions

We critically re-examine conductance in benzenedithiol (BDT)/gold junctions using real-time DFT simulations. Our results indicate a powerful influence of the BDT molecular charge on current, with negative charge suppressing electron transport. This effect occurs dynamically as the BDT charge and current oscillate on the femtosecond time scale, indicating that a steady-state picture may not be appropriate for this single molecule conducting device. Further, we exploit this effect to show that a gate voltage can be used to indirectly control the device current by adjusting the molecular charge. Thus, it appears that transport in even this simple molecular junction involves a level of sophistication not heretofore recognized.