金属fcc(100)表面吸附原子的自扩散现象

Self-diffusion of adatoms on metal fcc(100) surfaces

通过静态计算和分子动力学方法 ,系统地研究了吸附原子在金属fcc( 10 0 )表面的自扩散现象 ,所采用的模型势是一系列由原子嵌入方法 (EAM )得到的。结果表明金属fcc( 10 0 )表面可分为三种不同的类型 ,即硬、中性和软。而且发现在大多数表面 ,如硬的和许多中性表面的简单交换机制都是通过“应力产生和释放”的模型 ,而不是以前所认为“合作运动”模型 ,只有在软表面“合作运动”模型才变得重要。另外 ,在软表面上还观察到了另一种形式的复杂交换机制 ,它不同于“应力产生和释放”模型基础上的复杂交换机制。

Adatom diffusion mechanisms on metal fcc(100) surfaces is studied by a systematic static calculation and molecular dynamics based on a series of embedded atom method(EAM) potentials. The results suggest that the three kind of (100) surfaces named hard, middle and soft can be distinguished, and we find that the simple exchange mechanisms on the most of surfaces, e.g, hard and most middle surfaces, are in fact by the the model of the strain induced and relaxed' instead of the concerted motion' model as expected before. The concerted motion' model becomes important only on the soft surfaces. In addition, on the soft surfaces, another kind of complicated exchange mechanism which is different from that based on the strain induced and relaxed' model is observed.