Dresden 2014 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 27: Organic/bio Molecules on Metal Surfaces III

O 27.11: Vortrag

Dienstag, 1. April 2014, 13:00–13:15, TRE Phy

Force and Conductance in a Single Molecule Junction: SnPc on Ag(111) — •Nuala M. Caffrey, Cesar Lazo, Paolo Ferriani, and Stefan Heinze — Institut für Theoretische Physik und Astrophysik, Christian-Albrecht-Universität zu Kiel, D-24098 Kiel, Germany

Characterisation of the relationship between chemical force and electronic transport in an atomic scale junction is now possible with the combination of scanning tunnelling microscopy (STM) and atomic force microscopy (AFM) (e.g. [1]). Recent work in this area has concentrated mainly on atomic point contacts [2]. In this contribution, we determine, using density functional theory (DFT), the force experienced by an STM tip as it approaches the bistable tin-phtalocyanine (SnPc) molecule adsorbed on a Ag(111) surface. This molecule has been experimentally shown to have one of two possible conformations upon adsorption – either with the central Sn atom pointing away from (SnPc-up) or towards (SnPc-down) the surface [3]. We calculate the electronic transport through both conformations as a function of tip-molecule distance, i.e., in both the tunnelling and contact regime. We calculate the extent of the structural relaxations’ contribution to both the force and conductance and furthermore extract the correlation between the two.

[1] Hauptmann et al., New J Phys. 14, 073032 (2012)

[2] Ternes et al., Phys. Rev. Lett. 106, 016802 (2011)

[3] Wang et al., J. Am. Chem. Soc. 131, 3639 (2009)