Inelastic effects on the transport properties of alkanethiols

TL;DR

This study uses first-principles methods to analyze how inelastic effects and local heating influence electron transport in alkanethiols, revealing length-dependent temperature behaviors and odd-even effects in scattering profiles.

Contribution

It introduces a detailed first-principles analysis of inelastic scattering and local heating in alkanethiols, highlighting the impact of heat dissipation and molecular structure on transport properties.

Findings

Local temperature is insensitive to length without heat dissipation.

Temperature decreases with length when heat dissipation is considered.

Odd-even effect in inelastic scattering profiles matches experimental observations.

Abstract

Using first-principles approaches we investigate local heating and the inelastic contribution to the current for various alkanethiols sandwiched between metal electrodes. In the absence of good heat dissipation into the bulk electrodes, we find that the local temperature of the alkanethiols is relatively insensitive to their length. This is due to the rates of heating and cooling processes scaling similarly with length. On the other hand, when considering heat dissipation into the bulk electrodes, the local temperature of alkanethiols decreases as their length increases. We also find that the inelastic scattering profile displays an odd-even effect with length which compares well with experimental results. This effect is due to the alternating direction of the CH3 group motion with respect to current flow with increasing C atoms in the chain, and is very sensitive to the structure of the carbon-sulfur-gold bond. Inelastic scattering profiles can therefore help illuminate the bonding configuration of molecules to metallic surfaces.