Distribution of local elastic constants in nanofilms of metals Original Research Article

The distribution of local elastic constants of nanofilms was studied by the stress-fluctuation approach. The Lennard–Jones (L–J) and the second-moment approximation of tight-binding (TB-SMA) potential are used as models to investigate the differences between the pair-wise and many-body atomic interaction. Firstly the configurations of the nanofilm are obtained by the simulations, and then with the configurations, elastic constants are calculated. The behaviors of C11(n)C11(n) and C12(n)C12(n) are different for L–J films. Inner layers have larger C11(n)C11(n) and smaller C12(n)C12(n). For TB-SMA films, the distributions are different from L–J filmsʹ. The outmost layers have the smallest value, while the secondary outer layers have the largest and the behaviors of C11(n)C11(n) and C12(n)C12(n) are similar. This distribution can be explained by the competition between electron redistribution and lower coordination near the free surfaces. Compared to L–J model TB-SMA is better to describe the system. Furthermore, as the temperature increases, the elastic constants get larger while the distributions of the local elastic constants almost remain the same.