关键词: 分子动力学, 原子密度分布, 傅立叶变换, 晶体结构, 双晶

Abstract:

Ultra-large scale molecular dynamics simulations were used to investigate the breaking behavior of a [111]||[110] bicrystal copper nanowire. From the periodicity of the copper crystal structure, we developed a discrete Fourier transformation technique to analyze the periodic structure of the crystal system. In particular, the atomic density distribution along the long axis of the nanowire was transformed into a amplitude-frequency relation or into a
normalized atomic density distribution. These two treatments enable us to further study the crystal grain orientation and the crystal structure at different stretching moments of the nanowire. The amplitude-frequency analysis provided information about the large-scale crystallographic features while local characteristics were determined by the normalized atomic density distribution. From analyses of the simulation data, we found that the [111]||[110] bicrystal copper nanowire showed an amalgamation of the grain boundary and a rotation of the crystal grains during stretching and this led to a rupture in the [111] crystal grain. After breaking, the nanowire underwent a newrecrystallization process as determined by amplitude-frequency analysis and normalized atomic density distribution. The Fourier transformation technique proposed in this work provides a powerful tool for theoretical investigations of nanomaterials.

Key words: Molecular dynamics, Atomic density distribution, Fourier transformation, Crystal structure, Bicrystal