Universality in the transport response of molecular wires physisorbed onto graphene electrodes

TL;DR

This study investigates the transport properties of molecular wires on graphene electrodes, revealing a universal behavior of molecular resonances regardless of edge or positional variations, emphasizing the importance of proper k-sampling.

Contribution

It demonstrates the universality of molecular resonance positions in graphene-based molecular wires, independent of edge details and molecular positioning.

Findings

Resonance energies are universal for a given molecule.

Proper k-sampling is crucial for accurate conductance calculations.

Resonance positions do not depend on edge or gap details.

Abstract

We analyze the low-voltage transport response of large molecular wires bridging graphene electrodes, where the molecules are physisorbed onto the graphene sheets by planar anchor groups. In our study, the sheets are pulled away to vary the gap length and the relative atomic positions. The molecular wires are also translated in directions parallel and perpendicular to the sheets. We show that the energy position of the Breit-Wigner molecular resonances is universal for a given molecule, in the sense that it is independent of the details of the graphene edges, gaps lengths or of the molecule positions. We discuss the need to converge carefully the k-sampling to provide reasonable values of the conductance.