Structural Instability of Gold and Bimetallic Nanowires Using Monte Carlo Simulation

摘要

In this paper, we present a method for optimizing of metal nanostructures. The core of the method is a lattice Monte Carlo method with different lattices combined with an approach from molecular dynamics. Interaction between atoms is calculated using multi-body tight-binding model. The method allows solving of problems with periodic boundary conditions. It can be used for modeling of one-dimensional and two-dimensional atomic structures. If periodic boundary conditions are not given, we assume finite dimensions of the model lattice. In addition, automatic relaxation of the crystal lattice can be performed in order to minimize further the potential energy of the system. A computer implementation of the method is developed. It uses the commonly accepted XYZ format for describing atomic structures and passing input parameters. We perform two series of simulations to study the size, composition and temperature dependent surface segregation behaviors and structural atomic instability of Au-Ag nanowires. We found that the most stable mixing configuration of bimetallic nanowires has Ag-rich surface and Au-rich subsurface.