An ignition key for atomic-scale engines

TL;DR

This paper demonstrates how a nanoscale device can be activated to produce rotational atomic motion using current-induced forces, effectively serving as an ignition key for atomic-scale engines, with the activation linked to electronic structure features.

Contribution

It introduces a method to predict and induce non-conservative current-induced forces in atomic-scale devices using static electronic structure calculations.

Findings

Sharp activation of non-conservative forces at critical bias

Generalized rotational atomic motion observed

A static calculation method predicts non-conservative dynamics

Abstract

A current-carrying resonant nanoscale device, simulated by non-adiabatic molecular dynamics, exhibits sharp activation of non-conservative current-induced forces with bias. The result, above the critical bias, is generalized rotational atomic motion with a large gain in kinetic energy. The activation exploits sharp features in the electronic structure, and constitutes, in effect, an ignition key for atomic-scale motors. A controlling factor for the effect is the non-equilibrium dynamical response matrix for small-amplitude atomic motion under current. This matrix can be found from the steady-state electronic structure by a simpler static calculation, providing a way to detect the likely appearance, or otherwise, of non-conservative dynamics, in advance of real-time modelling.