The stress-fluctuation approach provides an useful tool to study the mechanical properties of materials. The stress-fluctuation approach and an analytical method were used to study the distribution of local elastic constants of nanofilms. The L-J and TB-SMA potentials were used as models to investigate the differences between the pair-wise and many-body atomic interaction of nanofilms. Both of simulation and analytical results show that for L-J nanofilms, layers near the free surface are softer than the interior layers, which is in agreement with previous reports, and for TB-SMA nanofilms, the outmost layers are softer, while the secondary outer layers are stiffer than the interior layers. Furthermore, as the temperature increases, both of the L-J and TB-SMA nanofilms are softened by the temperature effect%应力涨落法是一种研究材料力学性质的有效方法.采用应力涨落法和一种解析方法计算超低温纳米膜的局域弹性常数并分别以Lennard-Jones；(L-J)势和紧束缚势二阶矩(TB-SMA)近似为例,比较了两体势与多体势模型的不同.两种方法的结果都表明膜表面软于内部,而多体势(TB-SMA)模型膜中的次外层是最硬的.对比不同温度下应力涨落方法得到的结果,发现随着温度的升高两种势模型的纳米膜都会变软.
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