金原子纳米团簇的负热容现象的分子动力学模拟研究

Study on the negative heat capacities of Au nanoclusters by molecular dynamics simulation

文中采用微正则分子动力学方法模拟研究了原子数N =6 0到 6 75之间的 6种金原子纳米团簇从固态到液态的熔解过程 ,得到了势能和热容量随温度的变化关系。其结果表明 ,所模拟的 6种团簇在熔点附近出现负热容 ,通过对这些团簇熔解前后的势能以及结构变化的分析 ,探讨了产生负热容的微观机制。

The melting processes of Au_N(N=60,80,144,225,312 and 675) nanoclusters have been investigated by means of microcanonical molecular dynamics simulation technique. The curves of the potential energies and the heat capacities varying with the temperature are obtained. It is found that all of these six clusters have negative heat capacities around melting temperatures. To understand the micro-mechanism of the negative heat capacities, the differences of the structures of all the clusters at the temperatures just below and above the melting points are compared.