Cumulene Molecular Wire Conductance from First Principles

TL;DR

This paper uses first principles calculations to analyze the conductance of cumulene molecular wires, revealing oscillatory behavior and high conductance in odd-numbered carbon chains, indicating their potential for nanoelectronic applications.

Contribution

It provides the first ab initio NEGF-DFT analysis of cumulene wire conductance with realistic contacts, highlighting their metallic-like transport properties.

Findings

Odd-numbered cumulene wires have the highest conductance.

Conductance shows oscillatory dependence on the number of carbon atoms.

IVC is nearly linear within ±1 V bias.

Abstract

We present first principles calculations of current-voltage characteristics (IVC) and conductance of Au(111):S2-cumulene-S2:Au(111) molecular wire junctions with realistic contacts. The transport properties are calculated using full self-consistent ab initio NEGF-DFT methods under external bias. The conductance of the cumulene wires shows oscillatory behavior depending on the number of carbon atoms (double bonds). Among all conjugated oligomers, we find that cumulene wires with odd number of carbon atoms yield the highest conductance with metallic-like ballistic transport behavior. The reason is the high density of states in broad LUMO levels spanning the Fermi level of the electrodes. The transmission spectrum and the conductance depend only weakly on applied bias, and the IVC is nearly linear over a bias region from +1 to -1 V. Cumulene wires are therefore potential candidates for metallic connections in nanoelectronic applications.