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.
Bibliographical noteKAUST Repository Item: Exported on 2021-07-06
Acknowledgements: The authors are thankful to the King Abdullah University of Science and Technology (Kingdom of Saudi Arabia) for the financial support through the ACRAB project, to the Trinity College High-Performance Computer Center (TCHPC) and the Ireland’s High-Performance computing centre (ICHEC) for computational resources. Additional support was provided by the European Research Council (Quest and HINTS projects).
ASJC Scopus subject areas
- General Materials Science