Negative Differential Conductance in Nano-junctions: A Current Constrained Approach

TL;DR

This paper introduces a current constrained method to analyze negative differential conductance in molecular nano-junctions, emphasizing the role of auxiliary sites and electron correlations in transport behavior.

Contribution

It presents a novel current constrained approach for modeling negative differential conductance in nano-junctions with auxiliary sites.

Findings

Negative differential conductance depends on electron cooperativity.

Variable electron number influences conductance behavior.

Electron correlations are crucial for negative differential conductance.

Abstract

A current constrained approach is proposed to calculate negative differential conductance in molecular nano-junctions. A four-site junction is considered where a steady-state current is forced by inserting only the two central sites within the circuit. The two lateral sites (representing e.g. dangling molecular groups) do not actively participate in transport, but exchange electrons with the two main sites. These auxiliary sites allow for a variable number of electrons within the junction, while, as required by the current constrained approach, the total number of electrons in the system is kept constant. We discuss the conditions for negative differential conductance in terms of cooperativity, variability of the number of electrons in the junction, and electron correlations.