Gate control of artificial single-molecule electric machines

Artificial molecular machines are a growing field in nanoscience and nanotechnology. This study proposes a new class of artificial molecular machines, the second-generation single-molecule electric revolving doors (2G S-MERDs), a direct extension of our previous work [Hsu, L.-Y.; Li, E.-Y.; Rabitz, H. Nano Lett. 2013, 13, 5020]. We investigate destructive quantum interference with tunneling and conductance dependence upon molecular conformation in the 2G S-MERDs by using the Green's function method together with density functional theory. The simulations with four types of functionals (PBE, PZ, PW91, and BLYP) show that the 2G S-MERDs have a large on-off conductance ratio (>10⁴) and that their open and closed door states can be operated by an experimentally feasible external electric field (∼1 V/nm). In addition, the simulations indicate that the potential energy difference between the open and closed states of the S-MERDs can be engineered. Conductance-gate electric field characteristics are also introduced to illustrate the operation of the 2G S-MERDs.