Forces and conductances in a single-molecule bipyridine junction

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Abstract

Inspired by recent measurements of forces and conductances of bipyridine nanojunctions, we have performed density functional theory calculations of structure and electron transport in a bipyridine molecule attached between gold electrodes for seven different contact geometries. The calculations show that both the bonding force and the conductance are sensitive to the surface structure, and that both properties are in good agreement with experiment for contact geometries characterized by intermediate coordination of the metal atoms corresponding to a stepped surface. The conductance is mediated by the lowest unoccupied molecular orbital, which can be illustrated by a quantitative comparison with a one-level model. Implications for the interpretation of the experimentally determined force and conductance distributions are discussed.
Original languageEnglish
JournalPhysical Review B Condensed Matter
Volume72
Issue number24
Pages (from-to)241401
ISSN0163-1829
DOIs
Publication statusPublished - 2005

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Copyright 2005 American Physical Society

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