异种原子及原子团簇在Cu表面扩散势垒的静力学计算

STATIC CALCULATION OF DIFFUSION BARRIER TO HETEROGENEOUS ADATOMS AND CLUSTERS ON Cu SURFACES

利用分子动力学中的静态计算方法分别计算了单个增原子(Cu,Ag,Pd)以及二聚物(CuCu,AgAg,PdPd,CuAg,CuPd)在金属铜表面上的扩散势垒,并将计算结果进行了分析比较.结果表明:1)相对交换机制而言,Cu表面增原子和二聚物容易通过跳跃机制扩散;不同种类的增原子的跳跃扩散势垒的大小关系是E(Ag)<E(Cu)<E(Pd),而交换势垒则相反.2)二聚物在Cu(100)表面上的扩散势垒之间关系与单个增原子的情况相似;二聚物从亚稳态到平衡态的跳跃扩散势垒比平衡态到亚稳态的势垒小得多,说明二聚物易于通过联动方式扩散而不是进一步分离.3)二聚物中邻近同质原子或异质原子的存在对Cu表面原子的扩散势垒的影响很小.

The diffusion barrier of adatoms（Cu, Ag and Pd） and dimers（CuCu, AgAg, PdPd, CuAg, CuPd） on Cu surfaces is calculated by the static calculation method of molecular dynamical simulation. And the calculated results are carried on the analysis comparison. The results show that： 1） Adatoms and dimers migrate most easily via a jump mechanism diffusion under relative exchange condition, the relationship of jump barriers to different adatoms is E（Ag）〈E（Cu）〈E（Pd）, whereas the relationship of exchange barriers is the converse; 2） The relationship of jump barrier to dimers is similar to that of adatoms, the barrier of dimers for jump diffusion to go from the sub-stable to the equilibrium state is much smaller than that of the reverse, indicating that dimers diffuse more readily than they are dissociate; 3） The presence of homogeneous or heterogeneous atoms has little effect on the diffusion barrier of atoms in the dimers on Cu surfaces.