降温过程对Au24Cu19合金团簇结构变化影响

采用基于嵌入原子法的正则系综NVT分子动力学方法在原子尺度上计算了包含24个金原子和19个铜原子的Au24Cu19双金属团簇在急冷和连续降温过程中的结构演化.根据原子平均势能、主要原子键对数目以及原子堆积结构随温度的变化表明，随着温度的降低，团簇表现为铜原子在内，金原子和少量铜原子包覆在外的构型.在温度被降低到较高温度区间时，急冷降温过程中，键对数目呈高-低振荡变化；连续冷却过程中，键对数目则呈低-高振荡变化.在温度较低的区间，直至400K，这两个冷却条件下的键对数目表现为同步变化.

Effects of Cooling Processes on Structural Changes for an Au24Cu19 Alloy Cluster

The structural changes of a binary metal Au24Cu19 cluster containing 24 gold atoms and 19 copper atoms on quenching and continuously cooling procedure were studied by NVT molecular dynamics simulations within the framework based on the embedded atom method. On the analysis of average potential energy per atom， pair numbers of the main atom bond， and the atom packing structure varying with the temperature， the clusters presented the configuration that the inner part was the copper atoms， coated with the gold atoms and a few of copper atoms with the decrease of the temperature. At the relative high temperature regime， the pair numbers presented high low vibration changes during the process of quenching， whereas they presented low high vibration changes during the continuously cooling process. At the relative low temperature regime until 400K， the pair numbers were changed synchronously under both cooling conditions.