Crystal asymmetry induces single-atom chain formation in gold nanowires

TL;DR

This study uses computational methods to show that breaking the symmetry of gold nanowires, either through off-axis stretching or thermal fluctuations, enables the formation of single-atom chains, aligning with experimental observations.

Contribution

It reveals that crystal asymmetry is essential for single-atom chain formation in gold nanowires, a novel insight into nanowire elongation mechanisms.

Findings

Chain formation occurs only with broken crystal symmetry.

Off-axis stretching induces chain formation consistent with experiments.

Thermal fluctuations can also promote chain formation.

Abstract

We performed density functional theory and tight-binding molecular dynamics calculations to investigate the formation of suspended linear atom chains when stretching gold nanowires along the [110] crystal orientation. We determined that chain formation can occur only when the crystal symmetry is broken in the early stages of the elongation process. Such crystallographic asymmetry can be induced by stretching the wire along a slightly off-axis tensile direction or by introducing thermal fluctuations. Our observation of the off-axis formation of these chains agrees with experimental findings.