The Role of Polytetrahedral Structures in the Elongation and Rupture of Gold Nanowires

TL;DR

This study uses high-accuracy molecular dynamics simulations to investigate how polytetrahedral structures influence the elongation and rupture of gold nanowires, revealing their formation under certain conditions and impact on conductance.

Contribution

It demonstrates the formation of polytetrahedral structures in gold nanowires during elongation and their effect on conductance, using a validated ReaxFF forcefield for accurate simulations.

Findings

Polytetrahedral structures form in the amorphous neck regions of nanowires.

Formation of these structures reduces conductance quantization.

ReaxFF forcefield provides a balance of accuracy and computational efficiency.

Abstract

We report comprehensive high-accuracy molecular dynamics simulations using the ReaxFF forcefield to explore the structural changes that occur as Au nanowires are elongated, establishing trends as a function of both temperature and nanowire diameter. Our simulations and subsequent quantitative structural analysis reveal that polytetrahedral structures (e.g., icosahedra) form within the "amorphous" neck regions, most prominently for systems with small diameter at high temperature. We demonstrate that the formation of polytetrahedra diminishes the conductance quantization as compared to systems without this structural motif. We demonstrate that use of the ReaxFF forcefield, fitted to high-accuracy first principles calculations of Au, combines the accuracy of quantum calculations with the speed of semi-empirical methods.