The Role of Polytetrahedral Structures in the Elongation and Rupture of   Gold Nanowires
  We report comprehensive high-accuracy molecular dynamics simulations using the ReaxFF forcefield to explore the structural changes that occur as Au nanowires are elongated, establishing trends as a function of both temperature and nanowire diameter. Our simulations and subsequent quantitative structural analysis reveal that polytetrahedral structures (e.g., icosahedra) form within the "amorphous" neck regions, most prominently for systems with small diameter at high temperature. We demonstrate that the formation of polytetrahedra diminishes the conductance quantization as compared to systems without this structural motif. We demonstrate that use of the ReaxFF forcefield, fitted to high-accuracy first principles calculations of Au, combines the accuracy of quantum calculations with the speed of semi-empirical methods. 
Christopher R. Iacovella, William R. French, Brandon G. Cook, Paul   R.C. Kent, Peter T. Cummings
cond-mat.mtrl-sci cond-mat.mes-hall