熔融Cu55团簇在冷却过程中结构变化的分子动力学模拟

MODELING STRUCTURAL CHANGES ON COOLING A MOLTEN Cu_(55) CLUSTER BY MOLECULAR DYNAMICS

应用分子动力学研究了一个熔融Cu_(55)团簇冷却过程中变为二十面体的结构变化.根据原子密度分布函数和对分布函数随温度变化的分析表明,在降温过程中由于原子之间连续地交换位置,团簇结构发生了三个阶段的变化:首先形成三壳层结构,继之初步形成四壳层结构,并在团簇内部开始形成由13个原了组成的二十面体结构,最终形成原子分布于4个壳层内具有二十面体结构的Cu_(55)团簇.模拟中由原子密度分布函数确定了不同壳层的原子位置.

The structural change of a molten Cu55 cluster during cooling was investigated by molecular dynamics models. On the basis of analyses of atomic density functions and pair-distribution functions, it is shown that the structural change involves three stages owing to continuously interchang- ing positions among atoms. In the first stage, a three shell structure is formed in this cluster. Then, atoms in this cluster distribute in four shell, and meanwhile 13 atoms in the inner part of this cluster form an icosahedron. Finally, the icosahedral structure with 55 atoms is constructed. In this model, the shells are determined by atomic density functions.