(405e) GPU-Enabled Simulations of Size Effects On the Elongation and Rupture of Metallic Nanowires Using Many-Body Potentials

Understanding the formation of atomic scale point contacts via the mechanical deformation of metallic nanowires is important to the development of future nano- and molecular-electronic devices.  Molecular simulation has been used extensively to explore this behavior; however, simulations often use smaller system sizes, higher strain rates, and fewer independent measurements than experiment. Most simulations have relied on many-body potentials, such as the embedded atom model (EAM) and second-moment approximation to the tight-binding potential (TB-SMA). The use of many-body potentials, as opposed to pair potentials, is critical for the accurate description of surface properties, defects, and elastic moduli of metallic systems.¹ The EAM potential has recently been ported to run on graphical processing units (GPUs) with great success.² However, previous work from our group has shown that the TB-SMA potential provides a more accurate description of the structure and energy of the elongation of nanowires than EAM, when compared to density functional theory.³

Here, we discuss our recent porting of the TB-SMA potential to the GPU by extending the highly optimized object-oriented many-particle dynamics (HOOMD) package.⁴  We find that the GPU-based TB-SMA potential provides significant speedups relative to parallel CPU-based simulations for nanowire systems.  As a test of this work, we use the GPU-enabled TB-SMA potential to investigate the elongation and rupture of Au nanowires over a range of parameters.  The speed-up associated with the GPU enables us to more closely model experimental conditions, with larger wires, slower elongation rates, and more total state points available for study.

[1] F. Cleri and V. Rosta, Tight-binding potentials for transition metals and alloys, Physical Review B, 1993, 48(1) 22-33.

[2] I. V. Morozov, A. M. Kazennova, R.G. Bystryia, G.E. Normana, V.V. Pisareva, and V.V. Stegailova. Molecular dynamics simulations of the relaxation processes in the condensed matter on GPUs Computer Physics Communications 182(9): 1974-1978, 2011.

[3] Q. Pu, Y. Leng, L. Tsetseris, H. S. Park, S. T. Pantelides, and P. T. Cummings, “Molecular Dynamics Simulations of Stretched Gold Nanowires: the Relative Utility of Different Semiempirical Potentials,” J. Chem. Phys., 2007, 126, 144707.

[4] J. A. Anderson, C. D. Lorenz, and A. Travesset, “General Purpose Molecular Dynamics Simulations Fully Implemented on Graphics Processing Units,” J. Comp. Phys., 2008, 227(10), 5342-5359. http://codeblue.umich.edu/hoomd-blue