Electrical transport through a mechanically gated molecular wire

Research output: Contribution to journalResearch articleContributedpeer-review


  • C. Toher - , TUD Dresden University of Technology (Author)
  • R. Temirov - , Helmholtz-Zentrum Dresden-Rossendorf (Author)
  • A. Greuling - , University Osnabruck (Author)
  • F. Pump - , Chair of Materials Science and Nanotechnology, Austrian Academy of Sciences, Leibniz Institute of Polymer Research Dresden (Author)
  • M. Kaczmarski - , University Osnabruck (Author)
  • G. Cuniberti - , Chair of Materials Science and Nanotechnology, Austrian Academy of Sciences, Leibniz Institute of Polymer Research Dresden, Pohang University of Science and Technology (Author)
  • M. Rohlfing - , University Osnabruck (Author)
  • F. S. Tautz - , Helmholtz-Zentrum Dresden-Rossendorf (Author)


A surface-adsorbed molecule is contacted with the tip of a scanning tunneling microscope (STM) at a predefined atom. On tip retraction, the molecule is peeled off the surface. During this experiment, a two-dimensional differential conductance map is measured on the plane spanned by the bias voltage and the tip-surface distance. The conductance map demonstrates that tip retraction leads to mechanical gating of the molecular wire in the STM junction. The experiments are compared with a detailed ab initio simulation. We find that density functional theory (DFT) in the local density approximation (LDA) describes the tip-molecule contact formation and the geometry of the molecular junction throughout the peeling process with predictive power. However, a DFT-LDA-based transport simulation following the nonequilibrium Green's function (NEGF) formalism fails to describe the behavior of the differential conductance as found in experiment. Further analysis reveals that this failure is due to the mean-field description of electron correlation in the local density approximation. The results presented here are expected to be of general validity and show that, for a wide range of common wire configurations, simulations which go beyond the mean-field level are required to accurately describe current conduction through molecules. Finally, the results of the present study illustrate that well-controlled experiments and concurrent ab initio transport simulations that systematically sample a large configuration space of molecule-electrode couplings allow the unambiguous identification of correlation signatures in experiment.


Original languageEnglish
Article number155402
Number of pages12
JournalPhysical review. B
Issue number15
Publication statusPublished - 1 Apr 2011

External IDs

WOS 000289053300004
Scopus 79961099983
ORCID /0000-0002-9927-2879/work/142248477



  • Density-functional theory, Electrostatic potential profile, Derivative discontinuities, Conductance, Ptcda, Junctions, Au(111), Ag(111), Systems, Model