摘要:
以分子动力学理论和微正则系综模型为基础,采用嵌入原子方法对原子数为13～321的13个铜纳米团簇凝固过程进行模拟,主要研究了团簇热力学性质和低温下的原子分布结构.结果表明:凝固点与原子数关系曲线随原子数增加有一定变化规律,原子数较少时,曲线成较大幅度振荡下降,原子数较多时,成较小幅度振荡上升趋势;团簇在低温下具有球壳层和二维点阵型两种原子分布结构,其中心的13个原子结构分别具有Ih和D3h对称性;中心原子分布为D3h的团簇结构接近Fcc晶体,晶化在低于凝固点的450～350 K之间进行.
Abstract:
Based on the theory of molecular dynamics and the model of microcanonical ensemble, the structure and thermodynamic properties of Cun (n=13, 19, 43, 55, 79, 87, 135, 141, 177, 201, 225, 249 and 321) nanoclusters at low temperature were studied by the microcanonical ensemble model during the solidification processes. The results indicated that freezing temperature changed with cluster size in a regular way. The curve declined when the number of atoms of the cluster was small and ascended when the number was great. All copper clusters had 13 atoms in the center, but had crystal D3h and non-crystal Ih structures for different atom numbers. The temperature of crystallization was lower than the corresponding solidification points about 450-350 K.
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