Role of temperature in the formation and growth of gold monoatomic chains: A molecular dynamics study

Abstract

The effect of temperature on the formation and growth of monoatomic chains is investigated by extensive molecular dynamics simulations using a semiempirical potential based on the second-moment approximation to the tight-binding Hamiltonian. Gold nanowires, with an aspect ratio of $\ensuremath{\sim}$13 and a cross section of $\ensuremath{\sim}$1 $\mathrm{n}{\mathrm{m}}^{2}$, are stretched at a rate of 3 $\mathrm{m}/\mathrm{s}$ in the range of temperatures 5--600 K with 50 initial configurations per temperature. A detailed study on the probability to form monoatomic chains (MACs) is presented. Two domains are apparent in our simulations: one at $Tl100$ K, where MACs develop from crystalline disorder at the constriction, and the other at $Tg100$ K, where MACs form as a consequence of plastic deformation of the nanowire. Our results show that the average length of the formed MACs maximizes at $T=$150 K, which is supported by simple energy arguments.