Inspired by some recent experiments and numerical works related to nanoresonators, we perform classical molecular dynamics simulations to investigate the thermal expansion and the ability of the device to act as a strain sensor assisted by thermally-induced vibrations. The proposed model consists in a chain of atoms interacting anharmonically with both ends clamped to thermal reservoirs. We analyze the thermal expansion and resonant frequency shifts as a function of temperature and the applied strain. For the transversal modes the shift is approximately linear with strain. We also present analytical results from canonical calculations in the harmonic approximation showing that thermal expansion is uniform along the device. This prediction also works when the system operates in a nonlinear oscillation regime at moderate and high temperatures.

Inspired by some recent molecular dynamics (MD) simulations and experiments on suspended graphene nanoribbons, we study a simplified model where the atoms are disposed in a rectangular lattice coupled by nearest neighbor interactions which are quadratic in the interatomic distance. The system has a mechanical strain, and the border atoms are coupled to Langevin thermal baths. Atom masses vary linearly in the longitudinal direction, modeling an isotope or doping distribution. This asymmetry and tension modify thermal properties. Although the atomic interaction is quadratic, the potential is anharmonic in the coordinates. By direct MD simulations and solving Fokker-Planck equations at low temperatures, we can better understand the role of anharmonicities in thermal rectification. We observe an increasing thermal current with an increasing applied mechanical tension. The temperatures and thermal currents vary along the transverse direction. This effect can be useful to establish which parts of the system are more sensitive to thermal damage. We also study thermal rectification as a function of strain and system size. *

We calculate the thermal conductance of a structured silicon nanocrystal with a hole of different sizes. The numerical study is based on non-equilibrium molecular dynamics simulations using two potential models for the interatomic interactions: (i) an empirical Tersoff–Brenner (Tersoff) potential; (ii) a semi-empirical tight binding (TB) potential. TB potential model predicts a similar thermal conductance for the nanocrystal with no hole and with a small size hole, which contrasts with the monotonic decrease predicted by Tersoff potential model. In addition, thermal conductance decreasing is higher for TB potential model when the surface-to-volume ratio increases. This points out that to study thermal properties of nanostructures with high surface-to-volume ratio is mandatory the use of potential models with high transferability to take adequately into account the relevant quantum physical effects due to boundaries and surfaces.

In this work we compare different implementations of two interatomic potential models, one the empirical Tersoff–Brenner and the other the semi-empirical tight-binding, to be used in the thermal transport study of silicon nanosystems. The calculations are based on molecular dynamics simulations. In the case of Tersoff–Brenner potential, two free software packages were used, while for tight-binding potential, an in-house code was developed. Both approaches require an enormous amount of computing effort, so the use of acceleration tools for adequate performance is crucial. We present a detailed study of each computational tool used: efficiency, advantages and disadvantages, and the results of application to the calculation of thermal conductance of structured silicon nanocrystals subjected to a temperature gradient.