The Relation between Structure and Quantum Interference in Single Molecule Junctions

• Published in: Nano letters 2010-10, Vol.10 (10), p.4260-4265
• Main Authors: Markussen, Troels, Stadler, Robert, Thygesen, Kristian S.
• Format: Article
• Language: English
• Subjects: Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electron states; Exact sciences and technology; Methods of electronic structure calculations; Physics
• ISSN: 1530-6984; 1530-6992
• DOI: 10.1021/nl101688a

Quantum interference (QI) of electron pathways has recently attracted increased interest as an enabling tool for single-molecule electronic devices. Although various molecular systems have been shown to exhibit QI effects and a number of methods have been proposed for its analysis, simple guidelines linking the molecular structure to QI effects in the phase-coherent transport regime have until now been lacking. In the present work we demonstrate that QI in aromatic molecules is intimately related to the topology of the molecule’s π system and establish a simple graphical scheme to predict the existence of QI-induced transmission antiresonances. The generality of the scheme, which is exact for a certain class of tight-binding models, is proved by a comparison to first-principles transport calculations for 10 different configurations of anthraquinone as well as a set of cross-conjugated molecular wires.