A study published as a Letter in Nature , presents a new type of molecular junction that is more insulating than a vacuum region of the same dimensions as the active component. The effect is obtained by designing molecules with Quantum destructive interference, such that the molecules at relevant energies strongly suppresses electron conductance through the molecule. The transport calculations were performed using QuantumATK by Gemma Solomon’s group at the University of Copenhagen. Synthesis and experimental measurements of the conductance came from the groups of Shengxiong Xiao, Colin Nuckolls and Latha Venkataraman group at Shanghai Normal University and Columbia University. The molecules may find applications in thermo-electric devices or as insulators in electronic devices.
Figure 1. Schematic illustration of the attenuation of the wave function describing an electron tunnelling through a single-molecule junction. (a) Through a low-conducting molecule, here an alkane. (b) Through an empty junction, i.e., a vacuum-gap between the electrodes. (c) Through a molecule with non-exponential attenuation of the tunnelling probability due to destructive quantum interference.
All the computational methods used in the letter are available in QuantumATK and are described in the tutorials:
 M. H. Garner, H. Li, Y. Chen, T. A. Su, Z. Shangguan, D. W. Paley, T. Liu, F. Ng, H. Li, S. Xiao, C. Nuckolls, L. Venkataraman, and G. C. Solomon, "Comprehensive suppression of single-molecule conductance using destructive σ-interference", Nature 558, 415 (2018).