Inelastic current-voltage characteristics of atomic and molecular junctions

TL;DR

This paper uses first-principles calculations to analyze inelastic I-V characteristics of atomic and molecular junctions, revealing how vibrational modes influence electrical behavior and how these insights can determine contact structures.

Contribution

It provides the first-principles analysis of inelastic I-V characteristics in atomic and molecular junctions, highlighting the role of vibrational modes and contact structure sensitivity.

Findings

Discontinuities in I-V curves correspond to vibrational modes.

Results agree with experimental data for gold contacts.

Inelastic I-V curves can reveal contact bonding geometry.

Abstract

We report first-principles calculations of the inelastic current-voltage (I-V) characteristics of a gold point contact and a molecular junction in the nonresonant regime. Discontinuities in the I-V curves appear in correspondence to the normal modes of the structures. Due to the quasi-one-dimensional nature of these systems, specific modes with large longitudinal component dominate the inelastic I-V curves. In the case of the gold point contact, our results are in good agreement with recent experimental data. For the molecular junction, we find that the inelastic I-V curves are quite sensitive to the structure of the contact between the molecule and the electrodes thus providing a powerful tool to extract the bonding geometry in molecular wires.