Advanced Energy Technology, Lawrence Berkeley National Laboratory, Berkeley, CA 94720, USA.
J Phys Condens Matter. 2011 Nov 23;23(46):462201. doi: 10.1088/0953-8984/23/46/462201. Epub 2011 Oct 21.
The diffusion of two-dimensional adatom-islands (up to 100 atoms) on Cu(111) has been studied, using the self-learning kinetic Monte Carlo method (Trushin et al 2005 Phys. Rev. B 72 115401). A variety of multiple- and single-atom processes are revealed in the simulations, and the size dependences of the diffusion coefficients and effective diffusion barriers are calculated for each. From the tabulated frequencies of events found in the simulation, we show a crossover from diffusion due to the collective motion of the island to a regime in which the island diffuses through periphery-dominated mass transport. This crossover occurs for island sizes between 13 and 19 atoms. For islands containing 19-100 atoms the scaling exponent is 1.5, which is in good agreement with previous work. The diffusion of islands containing 2-13 atoms can be explained primarily on the basis of a linear increase of the barrier for the collective motion with the size of the island.
使用自学习的动力学蒙特卡罗方法（Trushin 等人，2005 年，Phys. Rev. B 72，115401），研究了二维吸附原子岛（最多 100 个原子）在 Cu(111) 上的扩散。在模拟中揭示了多种多原子和单原子过程，并计算了每种过程的扩散系数和有效扩散势垒的尺寸依赖性。从模拟中发现的事件频率表中，我们展示了由于岛的集体运动引起的扩散到通过边缘主导的质量输运的扩散的转变。这种转变发生在 13 到 19 个原子的岛大小之间。对于包含 19-100 个原子的岛屿，标度指数为 1.5，与之前的工作非常吻合。对于包含 2-13 个原子的岛屿的扩散，可以主要基于集体运动势垒随岛屿尺寸的线性增加来解释。
