Role of the Binding Motifs in the Energy Level Alignment and Conductance of Amine-Gold Linked Molecular Junctions within DFT and DFT plus σ

We investigate, using density functional theory (DFT), the electronic and conducting properties of benzenediamine connected to gold electrodes via different tip structures. We examine a series of binding motifs to the electrodes and calculate the junction spectral properties. We consider corrections to the position of molecular resonances at the junction and discuss different approaches to the calculation of these shifts. We relate the magnitude of these corrections to resonance energies to the atomistic structure of the tip. Benzenediamine DFT-based transmission spectra can be well approximated by a Lorentzian model involving only the highest occupied molecular orbital (HOMO). We show how benzenediamine calculated conductance values in quantitative agreement with previous experiments can be achieved from the combination of DFT-based spectra and corrections to the DFT-based HOMO energy and an accessible Lorentzian model.

Automated summary

Using density functional theory (DFT), the electronic and conducting properties of benzenediamine connected to gold electrodes via different tip structures were investigated. Different binding motifs and junction spectral properties were examined, with corrections to molecular resonances at the junction based on atomistic structure of the tip. DFT-based transmission spectra approximated by a Lorentzian model involving only the highest occupied molecular orbital (HOMO) can achieve conductance values in quantitative agreement with previous experiments.