Structural Characterization of the Rate-Dependent Energy Release Mechanism of Gold Nanowires Under Elongation

Understanding the underlying mechanisms of the formation of break-junction structures in metal nanowires has important implications in the area of molecular- and nano-electronics. Gold nanowires have been demonstrated to form single-atom and helical chains when stretched. The temperature and rate of elongation strongly dictate the length of these chains, e.g. long chains are favored for low temperature systems with fast elongation rates [1]. In this work we use molecular dynamics simulations of gold nanowires that utilize the tight-binding second-moment approximation potential (TB-SMA) to explore the rate-dependent energy release mechanisms that govern chain formation. We employ shape matching techniques based on spherical harmonics [2] to quantify the structural changes in the nanowires. We utilize these techniques to quantitatively identify dislocations in the crystal structure and transitions to non-crystalline local structures, as related to the energy release mechanisms.

[1] Pu Q, Leng YS, Cummings PT, Rate-Dependent Energy Release Mechanism of Gold Nanowires under Elongation, JACS 130 (52), 2008

[2] Iacovella CR, Keys AS, Horsch MA, Glotzer SC, Icosahedral packing of polymer-tethered nanospheres and stabilization of the gyroid phase, PRE 75(4), 2007