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Electrode-molecule energy level offsets in a gold-benzene diamine-gold single molecule tunnel junction.
Szepieniec, Mark S.
Greer, James C.
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.
Benzene diamine molecule , Molecule tunnel junctions , Density functional theory
Szepieniec, M. S. and Greer, J. C. (2020) 'Electrode-molecule energy level offsets in a gold-benzene diamine-gold single molecule tunnel junction', Journal of Chemical Physics, 153(17), 174104 (10pp). doi: 10.1063/5.0024567
© 2020, the Authors. Published under license by AIP Publishing. This article may be downloaded for personal use only. Any other use requires prior permission of the author(s) and AIP Publishing. This article appeared as: Szepieniec, M. S. and Greer, J. C. (2020) 'Electrode-molecule energy level offsets in a gold-benzene diamine-gold single molecule tunnel junction', Journal of Chemical Physics, 153(17), 174104 (10pp), doi: 10.1063/5.0024567, and may be found at https://doi.org/10.1063/5.0024567