Crystal asymmetry induces single-atom chain formation in gold nanowires

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.