EPL, 83 (2008) 58001
DOI: 10.1209/0295-5075/83/58001

Transport signature of pseudo Jahn-Teller dynamics in a single-molecule transistor

F. Reckermann^{1, 2, 3}, M. Leijnse^{1, 3}, M. R. Wegewijs^{1, 2, 3} and H. Schoeller<sup>1, 3

1</sup>  Institut für Theoretische Physik A, RWTH Aachen - 52056 Aachen, Germany, EU
²  Institut für Festkörper-Forschung - Theorie 3, Forschungszentrum Jülich - 52425 Jülich, Germany, EU
³  JARA - Fundamentals of Future Information Technology

received 14 February 2008; accepted in final form 17 July 2008; published September 2008
published online 19 August 2008

Abstract
We calculate the electronic transport through a molecular dimer, in which an excess electron is delocalized over equivalent monomers, which can be locally distorted. In this system the Born-Oppenheimer approximation breaks down resulting in quantum entanglement of the mechanical and electronic motion. We show that pseudo Jahn-Teller (pJT) dynamics of the molecule gives rise to conductance peaks that indicate this violation. Their magnitude, sign and position sharply depend on the electro-mechanical properties of the molecule, which can be varied in recently developed three-terminal junctions with mechanical control. The predicted effect depends crucially on the degree of intramolecular delocalization of the excess electron, a parameter which is also of fundamental importance in physical chemistry.

PACS
85.65.+h - Molecular electronic devices.
71.70.Ej - Spin-orbit coupling, Zeeman and Stark splitting, Jahn-Teller effect.
85.85.+j - Micro- and nano-electromechanical systems (MEMS/NEMS) and devices.

© EPLA 2008