title: Functionality in single-molecule devices: model calculations and applications of the inelastic electron tunneling signal in molecular junctions.
abstract: We analyze how functionality could be obtained within single-molecule devices by using a combination of non-equilibrium Green's functions and ab initio calculations to study the inelastic transport properties of single-molecule junctions. First, we apply a full non-equilibrium Green's function technique to a model system with electron-vibration coupling. We show that the features in the inelastic electron tunneling spectra (IETS) of the molecular junctions are virtually independent of the nature of the molecule-lead contacts. Since the contacts are not easily reproducible from one device to another, this is a very useful property. The IETS signal is much more robust versus modifications at the contacts and hence can be used to build functional nanodevices. Second, we consider a realistic model of a organic conjugated molecule. We use ab initio calculations to study how the vibronic properties of the molecule can be controlled by an external electric field which acts as a gate voltage. The control, through the gate voltage, of the vibron frequencies and (more importantly) of the electron-vibron coupling enables the construction of functionality: nonlinear amplification and/or switching is obtained from the IETS signal within a single-molecule device.
authors.affiliation: Department of Physics, University of York, Heslington, York YO10 5DD, United Kingdom. louise.dash@york.ac.uk
authors.forename: L K
authors.initials: LK
authors.lastname: Dash
authors.forename: H
authors.initials: H
authors.lastname: Ness
authors.forename: M J
authors.initials: MJ
authors.lastname: Verstraete
authors.forename: R W
authors.initials: RW
authors.lastname: Godby