应用正则系综分子动力学方法和嵌入原子势函数, 模拟计算了在升温过程中纳米尺度铜团簇Cun(原子数n=531, 603, 683)原子径向密度分布函数ρ(r)及原子的平均能量随温度的变化. 在将团簇沿其径向分为表层、近表层、内层I和内层II四个区域后, 研究了在升温过程中纳米尺度铜团簇表层及内部区域结构变化.结果表明, 团簇Cu603在温度为770 K时团簇表层区域原子的结构部分处于无序状态, 部分保持有序结构, 且这种有序和无序共存的状态一直持续到1000 K, 而在这一温度区间内, 近表层和内层原子的结构仍总体保持有序结构;在1000—1100 K温度区间内, 各区域原子的平均能量均经历一个N形变化后,当温度为1080 K时团簇各区域内原子的结构已变为无序, 但沿径向方向表现为层状分布; 直到1500 K时, 团簇的层状分布特征消失. 团簇Cu531和Cu683具有相似的结果.
Molecular dynamics simulation were used to study the variations of atom radial density distribution profilesρ(r) and internal energy per atom with temperatures for Cun(n=531,603,683) clusters. The studied cluster could be divided into four parts of surface layer and approximate surface layer, etc. according to the calculations ofρ(r). The simulated results show that parts of Cu603 cluster surface layer have been found in the state of disorder, while the rest of the cluster surface layer remains orderly when the temperature is around 770K. The coexistence of order and disorder has been lasting until the temperature of 1000K. The atomic structure of approximate surface layer and inner layer keeps in order as a whole between the temperature of 770K and 1000K. After variation of internal energy per atom with temperature undergo the shape of the letter N during 1000K-1100K, the atomic structure of individual parts of cluster has changed into disorderly at 1080K, but the radial direction of cluster appears layered distribution. The layered distribution of cluster disappears till the temperature of 1500K.
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