On simulation of local fluxes in molecular junctions

TL;DR

This paper reviews methods for simulating local current densities in molecular junctions, highlighting their advantages, limitations, and the importance of basis choice, with numerical examples illustrating key concepts.

Contribution

It provides a pedagogical overview of current density simulation in molecular junctions, emphasizing its advantages over bond currents and discussing sensitivities and conservation issues.

Findings

Current density offers more detailed information than bond currents.

Simulations are sensitive to basis set and electronic structure methods.

Numerical examples demonstrate local current conservation considerations.

Abstract

We present a pedagogical review of current density simulation in molecular junction models indicating its advantages and deficiencies in analysis of local junction transport characteristics. In particular, we argue that current density is a universal tool which provides more information than traditionally simulated bond currents, especially when discussing inelastic processes. However, current density simulations are sensitive to choice of basis and electronic structure method. We note that discussing local current conservation in junctions one has to account for source term caused by open character of the system and intra-molecular interactions. Our considerations are illustrated with numerical simulations of a benzenedithiol molecular junction.