Quantitative Current-Voltage Characteristics in Molecular Junctions from First Principles

TL;DR

This paper demonstrates that self-energy-corrected DFT combined with a scattering-state approach can accurately predict current-voltage characteristics in molecular junctions, advancing the understanding of charge transport at the molecular scale.

Contribution

The authors introduce a parameter-free self-energy correction to DFT and an approximate method for predicting IV characteristics, improving accuracy and computational efficiency.

Findings

Quantitative agreement with experimental IV measurements.

Standard DFT significantly underestimates currents.

Proposed linear response approach predicts IV for various junctions.

Abstract

Using self-energy-corrected density functional theory (DFT) and a coherent scattering-state approach, we explain current-voltage (IV) measurements of four pyridine-Au and amine-Au linked molecular junctions with quantitative accuracy. Parameter-free many-electron self-energy corrections to DFT Kohn-Sham eigenvalues are demonstrated to lead to excellent agreement with experiments at finite bias, improving upon order-of-magnitude errors in currents obtained with standard DFT approaches. We further propose an approximate route for prediction of quantitative IV characteristics for both symmetric and asymmetric molecular junctions based on linear response theory and knowledge of the Stark shifts of junction resonance energies. Our work demonstrates that a quantitative, computationally inexpensive description of coherent transport in molecular junctions is readily achievable, enabling new understanding and control of charge transport properties of molecular-scale interfaces at large bias voltages.