Modeling inelastic phonon scattering in atomic- and molecular-wire junctions

TL;DR

This paper introduces computationally efficient approximations for modeling inelastic phonon scattering in atomic and molecular wire junctions, validated against first-principles calculations and experimental data.

Contribution

It develops simplified analytical models from the non-equilibrium Green's function method that accurately reproduce complex calculations and experimental results.

Findings

Quantitative agreement with full NEGF calculations.

Simplified models reduce computational effort significantly.

Models fit experimental conductance data for gold wires and hydrogen molecules.

Abstract

Computationally inexpensive approximations describing electron-phonon scattering in molecular-scale conductors are derived from the non-equilibrium Green's function method. The accuracy is demonstrated with a first principles calculation on an atomic gold wire. Quantitative agreement between the full non-equilibrium Green's function calculation and the newly derived expressions is obtained while simplifying the computational burden by several orders of magnitude. In addition, analytical models provide intuitive understanding of the conductance including non-equilibrium heating and provide a convenient way of parameterizing the physics. This is exemplified by fitting the expressions to the experimentally observed conductances through both an atomic gold wire and a hydrogen molecule.