Han Yong, Evans James W
Ames National Laboratory, U.S. Department of Energy, Ames, Iowa 50011, USA.
Department of Physics and Astronomy, Iowa State University, Ames, Iowa 50011, USA.
J Chem Phys. 2024 Aug 21;161(7). doi: 10.1063/5.0221012.
Stochastic lattice-gas models provide the natural framework for analysis of the surface diffusion-mediated evolution of crystalline metal nanostructures on the appropriate time scale (often 101-104 s) and length scale. Model behavior can be precisely assessed by kinetic Monte Carlo simulation, typically incorporating a rejection-free algorithm to efficiently handle the broad range of Arrhenius rates for hopping of surface atoms. The model should realistically prescribe these rates, or the associated barriers, for a diversity of local surface environments. However, commonly used generic choices for barriers fail, even qualitatively, to simultaneously describe diffusion for different low-index facets, for terrace vs step edge diffusion, etc. We introduce an alternative Unconventional Interaction-Conventional Interaction formalism to prescribe these barriers, which, even with few parameters, can realistically capture most aspects of behavior. The model is illustrated for single-component fcc metal systems, mainly for the case of Ag. It is quite versatile and can be applied to describe both the post-deposition evolution of 2D nanostructures in homoepitaxial thin films (e.g., reshaping and coalescence of 2D islands) and the post-synthesis evolution of 3D nanocrystals (e.g., reshaping of nanocrystals synthesized with various faceted non-equilibrium shapes back to 3D equilibrium Wulff shapes).
随机晶格气体模型为在适当的时间尺度（通常为101 - 104秒）和长度尺度上分析晶体金属纳米结构的表面扩散介导演化提供了自然框架。模型行为可以通过动力学蒙特卡罗模拟精确评估，通常采用无拒绝算法来有效处理表面原子跳跃的广泛阿仑尼乌斯速率范围。该模型应该针对各种局部表面环境实际规定这些速率或相关势垒。然而，常用的势垒通用选择甚至在定性上都无法同时描述不同低指数晶面的扩散、平台与台阶边缘扩散等情况。我们引入了一种替代的非常规相互作用 - 常规相互作用形式来规定这些势垒，即使参数很少，它也能实际捕捉行为的大多数方面。该模型以单组分面心立方金属系统为例进行说明，主要针对银的情况。它非常通用，可用于描述同质外延薄膜中二维纳米结构的沉积后演化（例如二维岛的重塑和合并）以及三维纳米晶体的合成后演化（例如将具有各种多面非平衡形状合成的纳米晶体重塑回三维平衡的伍尔夫形状）。
