Mo纳米薄膜热力学性质的分子动力学模拟

采用改进嵌入原子法(MAEAM)，通过经典的分子动力学(MD)模拟计算了高熔点过渡金属体心立方(bcc) Mo块体Gibbs自由能和表面能. 对于纳米薄膜的热力学数据，比如Gibbs自由能等，可以看成是薄膜内部原子和表面原子两部分数据之和，然后根据薄膜的体表原子之比就可以直接计算出总的自由能，并由此可以得到热力学性质与薄膜尺寸及温度的定量关系式. 分别计算了bcc Mo块体及其纳米尺寸薄膜的自由能和热容，结果表明，Mo纳米薄膜的热力学性质具有尺寸效应，并且在薄膜尺寸小于15—20nm时，这种效应变得非常明 关键词： 改进嵌入原子法 Mo纳米薄膜 表面自由能 热容

Thermal dynamics properties of bcc Mo nanofilm from MD simulation

Using molecular dynamics simulation with the modified analytic embedded-atom method (MAEAM), we calculated Gibbs free energy and surface free energy of bcc Mo with high melting temperature T_f, and further obtained the Gibbs free energy of its nanofilms. Based on the Gibbs free energy of nanofilms, we investigated the heat capacity of molybdenum nanofilms at constant pressure or at constant volume. The analysis reveals that the molar heat capacity of bulk sample is lower than that of the nanofilms, and the difference increases with the decrease of the film thickness. It is also observed that such size effect of Mo nanofilm is not really significant until the thickness is less than about 15—20nm. It is the surface atoms that determine the size effect on the thermodynamic properties of nanofilms. The difference between C_V and C_P of nanofilms is firstly analysed quantitatively and the calculated result for C_V/C_P varies linearly with T/T_f and relates directly to film thickness.