title: Probing the Statistical Validity of the Ductile-to-Brittle Transition in Metallic Nanowires Using GPU Computing.
abstract: We perform a large-scale statistical analysis (>2000 independent simulations) of the elongation and rupture of gold nanowires, probing the validity and scope of the recently proposed ductile-to-brittle transition that occurs with increasing nanowire length [Wu et al. Nano Lett. 2012, 12, 910-914]. To facilitate a high-throughput simulation approach, we implement the second-moment approximation to the tight-binding (TB-SMA) potential within HOOMD-Blue, a molecular dynamics package which runs on massively parallel graphics processing units (GPUs). In a statistical sense, we find that the nanowires obey the ductile-to-brittle model quite well; however, we observe several unexpected features from the simulations that build on our understanding of the ductile-to-brittle transition. First, occasional failure behavior is observed that qualitatively differs from that predicted by the model prediction; this is attributed to stochastic thermal motion of the Au atoms and occurs at temperatures as low as 10 K. In addition, we also find that the ductile-to-brittle model, which was developed using classical dislocation theory, holds for nanowires as small as 3 nm in diameter. Finally, we demonstrate that the nanowire critical length is higher at 298 K relative to 10 K, a result that is not predicted by the ductile-to-brittle model. These results offer practical design strategies for adjusting nanowire failure and structure and also demonstrate that GPU computing is an excellent tool for studies requiring a large number of independent trajectories in order to fully characterize a system's behavior.
authors.affiliation: Department of Chemical and Biomolecular Engineering, Vanderbilt University , Nashville, Tennessee, United States.
authors.forename: William R
authors.initials: WR
authors.lastname: French
authors.affiliation: Department of Chemical and Biomolecular Engineering, Vanderbilt University , Nashville, Tennessee, United States.
authors.forename: Amulya K
authors.initials: AK
authors.lastname: Pervaje
authors.affiliation: Department of Chemical and Biomolecular Engineering, North Carolina State University , Raleigh, North Carolina, United States.
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Santos
authors.affiliation: Department of Chemical and Biomolecular Engineering, Vanderbilt University , Nashville, Tennessee, United States.
authors.forename: Christopher R
authors.initials: CR
authors.lastname: Iacovella
authors.affiliation: Department of Chemical and Biomolecular Engineering, Vanderbilt University , Nashville, Tennessee, United States.|Center for Nanophase Materials Sciences, Oak Ridge National Laboratory , Oak Ridge, Tennessee, United States.
authors.forename: Peter T
authors.initials: PT
authors.lastname: Cummings