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Article

Molecular Conductance: Chemical Trends of Anchoring Groups

San-Huang Ke,^†^‡ Harold U. Baranger,*^‡ and Weitao Yang*^†;

Contribution from the Department of Chemistry, Duke University, Durham, North Carolina 27708-0354, and Department of Physics, Duke University, Durham, NC 27708-0305

J. Am. Chem. Soc., 2004, 126 (48), pp 15897–15904

DOI: 10.1021/ja047367e

Publication Date (Web): November 12, 2004

†

Department of Chemistry.

‡

Department of Physics.

In papers with more than one author, the asterisk indicates the name of the author to whom inquiries about the paper should be addressed.

baranger@phy.duke.edu; yang@chem.duke.edu

Abstract

Combining density functional theory calculations for molecular electronic structure with a Green function method for electron transport, we calculate from first principles the molecular conductance of benzene connected to two Au leads through different anchoring atomsS, Se, and Te. The relaxed atomic structure of the contact, different lead orientations, and different adsorption sites are fully considered. We find that the molecule−lead coupling, electron transfer, and conductance all depend strongly on the adsorption site, lead orientation, and local contact atomic configuration. For flat contacts the conductance decreases as the atomic number of the anchoring atom increases, regardless of the adsorption site, lead orientation, or bias. For small bias this chemical trend is, however, dependent on the contact atomic configuration: an additional Au atom at the contact with the (111) lead changes the best anchoring atom from S to Se, although for large bias the original chemical trend is recovered.