Berlin 2018 – scientific programme

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TT: Fachverband Tiefe Temperaturen

TT 74: Molecular Electronics and Photonics

TT 74.3: Talk

Wednesday, March 14, 2018, 16:30–16:45, H 3005

Current-induced bond rupture in molecular junctions — •André Erpenbeck¹, Uri Peskin², and Michael Thoss^{1, 3} — ¹Theoretische Physik, Friedrich-Alexander-Universität Erlangen-Nürnberg, Staudtstr. 7/B2, 91058 Erlangen, Germany — ²Schulich Faculty of Chemistry & Lise Meitner Center for Computational Quantum Chemistry, Technion-Israel Institute of Technology, Haifa 32000, Israel — ³Physikalisches Institut, Albert-Ludwigs-Universität Freiburg, Hermann-Herder-Strasse 3, 79104 Freiburg, Germany

Coupling between electronic and vibrational degrees of freedom in molecular junctions is an important mechanism, which influences the conductance properties. It also causes current-induced vibrational excitation, which may trigger bond rupture and is thus crucial in the context of the stability of molecular junctions. In this contribution, we study current-induced dissociation in molecular junctions based on representative models. To this end, we apply the hierarchical quantum master equation approach to the electronic transport problem. For the treatment of the nuclear degree of freedom, modeled with dissociative potentials, two different levels of theory are considered, (i) a quantum-classical description within the Ehrenfest approach and (ii) a fully quantum mechanical treatment using a discrete variable representation. Comparing the two approaches, we identify different processes leading to current-induced dissociation such as transient population of anti-bonding states by tunneling electrons or current-induced heating of the nuclear motion. The significance of the processes and their dependence on different model parameters is discussed in some detail.