Orbital interaction mechanisms of conductance enhancement and rectification by dithiocarboxylate anchoring group

Li, Zhenyu, and Kosov, Daniel S. (2006) Orbital interaction mechanisms of conductance enhancement and rectification by dithiocarboxylate anchoring group. Journal of Physical Chemistry Part B, 110 (39). pp. 19116-19120.

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Abstract

We study computationally the electron transport properties of dithiocarboxylate terminated molecular junctions. Transport properties are computed self-consistently within density functional theory and nonequilibrium Green's functions formalism. A microscopic origin of the experimentally observed current amplification by dithiocarboxylate anchoring groups is established. For the 4,4'-biphenyl bis(dithiocarboxylate) junction, we find that the interaction of the lowest unoccupied molecular orbital (LUMO) of the dithiocarboxylate anchoring group with LUMO and highest occupied molecular orbital (HOMO) of the biphenyl part results in bonding and antibonding resonances in the transmission spectrum in the vicinity of the electrode Fermi energy. A new microscopic mechanism of rectification is predicted based on the electronic structure of asymmetrical anchoring groups. We show that the peaks in the transmission spectra of 4'-thiolato-biphenyl-4-dithiocarboxylate junction respond differently to the applied voltage. Depending upon the origin of a transmission resonance in the orbital interaction picture, its energy can be shifted along with the chemical potential of the electrode to which the molecule is more strongly or more weakly coupled.

Item ID: 26471
Item Type: Article (Research - C1)
ISSN: 1520-5207
Date Deposited: 21 Jun 2013 00:19
FoR Codes: 02 PHYSICAL SCIENCES > 0204 Condensed Matter Physics > 020403 Condensed Matter Modelling and Density Functional Theory @ 50%
03 CHEMICAL SCIENCES > 0307 Theoretical and Computational Chemistry > 030701 Quantum Chemistry @ 50%
SEO Codes: 97 EXPANDING KNOWLEDGE > 970102 Expanding Knowledge in the Physical Sciences @ 100%
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