Current Streamline Flow on Current-induced Effects in Highly Asymmetric Molecular Junctions

TL;DR

This paper investigates how current density influences forces and inelastic effects in asymmetric molecular junctions, revealing potential for atomic-scale motors and highlighting the importance of current flow patterns.

Contribution

It demonstrates the critical role of current density in determining forces and inelastic effects, introducing a new perspective for designing molecular-scale devices.

Findings

Current-induced forces depend on current density distribution.

Asymmetric molecules can experience net torque from current flow.

Selection rules for inelastic effects can be misleading without current density details.

Abstract

From first-principles approaches, we illustrate that the current-induced forces and the selection rule for inelastic effects are highly relevant to the current density in an asymmetric molecular junction. The curved flow of current streamline around the asymmetric molecule may induce a net torque, which tends to rotate the benzene molecule, similar to the way a stream of water rotates a waterwheel. Thus, the Pt/benzene junction offers a practical system in the exploration of the possibility of atomic-scale motors. We also enumerate examples to show that the use of selection rule can lead to misjudgement of the importance of normal modes in the inelastic profiles when the detailed information about the current density is not considered.