中文摘要：

利用紧束缚分子动力学的方法研究厚度为0．5～10．4nm自由表面铅纳米薄膜的熔化温度。结果表明，铅纳米薄膜的熔化温度随着薄膜厚度的减小而降低，定量的数值结果与热力学模型预测相一致。薄膜厚度大于3个原子层时才有确定的熔化温度，而单原子层膜和双原子层膜在熔化前就已经破裂。对于自由表面的纳米薄膜，薄膜的熔化从上下表面开始，并逐渐向薄膜的中心逼近，这不同于自由表面纳米粒子的熔化过程，即先表层熔化后内部瞬间熔化。薄膜的熔化开始温度要低于熔化结束温度，这和相应块体材料的熔化温度明显不同。

英文摘要：

The tight-binding molecular dynamics method was used to study the size dependent melting temperature of Pd nanofilms with thickness of 0.5 - 10. 4 nm. The results show that the melting temperature of Pb nanofilms decreases with decreasing the film thickness, and the simulated results are consistent with the predictions of thermodynamic model. The Pb films with more than 3 atomic layers have specified melting temperature, but not for these with less than 3 atomic layers. The melting of nanofilms starts from the surface and then approaches to the center of the films, which is different from those of nanoparticles with free surface （the surface shell melts first, and then the interior core melts instantaneous）. Furthermore, the temperature of finishing melting is higher than that of beginning, which is different from those of the corresponding bulk materials.