Single molecule electron transport junctions: Charging and geometric effects on conductance

David Q. Andrews*, Revital Cohen, Richard P. Van Duyne, Mark A. Ratner

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

70 Scopus citations


A p -benzenedithiolate (BDT) molecule covalently bonded between two gold electrodes has become one of the model systems utilized for investigating molecular transport junctions. The plethora of papers published on the BDT system has led to varying conclusions with respect to both the mechanism and the magnitude of transport. Conductance variations have been attributed to difficulty in calculating charge transfer to the molecule, inability to locate the Fermi energy accurately, geometric dispersion, and stochastic switching. Here we compare results obtained using two transport codes, TRANSIESTA-C and HÜCKEL-IV, to show that upon Au-S bond lengthening, the calculated low bias conductance initially increases by up to a factor of 30. This increase in highest occupied molecular orbital (HOMO) mediated conductance is attributed to charging of the terminal sulfur atom and a corresponding decrease in the energy gap between the Fermi level and the HOMO. Addition of a single Au atom to each terminal of the extended BDT molecule is shown to add four molecular states near the Fermi energy, which may explain the varying results reported in the literature.

Original languageEnglish (US)
Article number174718
JournalJournal of Chemical Physics
Issue number17
StatePublished - 2006

ASJC Scopus subject areas

  • General Physics and Astronomy
  • Physical and Theoretical Chemistry


Dive into the research topics of 'Single molecule electron transport junctions: Charging and geometric effects on conductance'. Together they form a unique fingerprint.

Cite this