The vibration behavior of doubly clamped silicon nanowires with square cross sections is studied by molecular dynamics method. Silicon nanowires have lengths ranging from 4.888 to 12.491 nm and cross sections ranging from 1.22 nm × 1.22 nm to 3.39 nm × 3.39 nm. The size dependence of the resonant frequency is studied in detail. The results show that the vibration behavior of Si nanowire is quite different from the macroscopic beam, and the resonant frequency is much higher than the result based on the continuum theory, but close to the theoretical result based on the semicontinuum approach. Surface reconstruction can strongly affect on vibration behavior. These results demonstrate that the classic theory may not be suitable for analysis of performances of nanostructures, and the conclusion of the study has a certain practical significance on related fields.

Molecular dynamics simulations are carried out to characterize the mechanical properties of [001] and [110] oriented silicon nanowires, with the thickness ranging from 1.05nm to 3.24 nm. The nanowires are taken to have ideal surfaces and (2×1) reconstructed surfaces, respectively. A series of simulations for square cross-section Si nanowires have been performed and Young’s modulus is calculated from energy–strain relationship. The results show that the elasticity of Si nanowires is strongly depended on size and surface reconstruction. Furthermore, the physical origin of above results is analyzed, consistent with the bond loss and saturation concept. The results obtained from the molecular dynamics simulations are in good agreement with the values of first-principles. The molecular dynamics simulations combine the accuracy and efficiency.

In this paper, we investigate Young's modulus of Si nanofilms and Si nanowires under surface reconstruction with different temperature range from 100K to 800K by Molecular dynamics simulations. Young's modulus is calculated from energy-strain relationship. The results show that the Young's modulus of Si nanofilms decreases as temperature increases. The temperature effect on Young's modulus of Si nanowires also could not be ignored. Surface effect on nanostructures is more significant than on macrostructures, and Si nanostructures are more sensitive to heat.

We use molecular dynamical software Material StudioTM to investigate Young's moduli of Silicon nanowires along [001], [110] and [111] directions. Young's moduli for various directional and sized specimens are obtained via the energy-strain curves. The study suggests that the Young's modulus decreases as the thickness of the specimen decreases especially for the [001] direction, which display the peculiarity of anisotropy and size dependence. In comparison with the bulk silicon, the overall nanowires become soften for all the three directions. With respect to the results reported, similar trend is observed but magnitude of Young's modulus is not the same with each other. We analyze the dependence of Young's modulus on the size, surface structure and boundary conditions.