title: The image charge effect and vibron-assisted processes in Coulomb blockade transport: a first principles approach.
abstract: We present a combination of density functional theory and of both non-equilibrium Green's function formalism and a Master equation approach to accurately describe quantum transport in molecular junctions in the Coulomb blockade regime. We apply this effective first-principles approach to reproduce the experimental results of Perrin et al., [Nat. Nanotechnol., 2013, 8, 282] for the transport properties of a Au-(Zn)porphyrin-Au molecular junction. We demonstrate that energy level renormalization due to the image charge effect is crucial to the prediction of the current onset in the current-voltage, I-V, curves as a function of electrode separation. Furthermore, we show that for voltages beyond that setting the current onset, the slope of the I-V characteristics is determined by the interaction of the charge carriers with molecular vibrations. This corresponds to current-induced local heating, which may also lead to an effective reduced electronic coupling. Overall our scheme provides a fully ab initio description of quantum transport in the Coulomb blockade regime in the presence of electron-vibron coupling.
authors.affiliation: School of Physics, CRANN and AMBER, Trinity College, Dublin 2, Ireland. asouza@uni-mainz.de.
authors.forename: A M
authors.initials: AM
authors.lastname: Souza
authors.forename: I
authors.initials: I
authors.lastname: Rungger
authors.forename: U
authors.initials: U
authors.lastname: Schwingenschlögl
authors.forename: S
authors.initials: S
authors.lastname: Sanvito