Electrode-molecule energy level offsets in a gold-benzene diamine-gold single molecule tunnel junction

Szepieniec, Mark S. and Greer, James C. (2020) Electrode-molecule energy level offsets in a gold-benzene diamine-gold single molecule tunnel junction. The Journal of Chemical Physics, 153 (17). p. 174104. ISSN 0021-9606

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Abstract

One means for describing electron transport across single molecule tunnel junctions (MTJs) is to use density functional theory (DFT) in conjunction with a nonequilibrium Green's function formalism. This description relies on interpreting solutions to the Kohn-Sham (KS) equations used to solve the DFT problem as quasiparticle (QP) states. Many practical DFT implementations suffer from electron self-interaction errors and an inability to treat charge image potentials for molecules near metal surfaces. For MTJs, the overall effect of these errors is typically manifested as an overestimation of electronic currents. Correcting KS energies for self-interaction and image potential errors results in MTJ current-voltage characteristics in close agreement with measured currents. An alternative transport approach foregoes a QP picture and solves for a many-electron wavefunction on the MTJ subject to open system boundary conditions. It is demonstrated that this many-electron method provides similar results to the corrected QP picture for electronic current. The analysis of these two distinct approaches is related through corrections to a junction's electronic structure beyond the KS energies for the case of a benzene diamine molecule bonded between two gold electrodes.

Item Type: Article
Keywords: Electronic transport ; Potential energy barrier; Wigner functions; Density functional theory; Configuration interaction ; Quasiparticle; Current-voltage characteristic ; Green-functions technique
Schools/Departments: University of Nottingham Ningbo China > Faculty of Science and Engineering > Department of Electrical and Electronic Engineering
Identification Number: https://doi.org/10.1063/5.0024567
Depositing User: Wu, Cocoa
Date Deposited: 03 Dec 2020 06:00
Last Modified: 03 Dec 2020 06:00
URI: http://eprints.nottingham.ac.uk/id/eprint/63914

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