Investigating the effect of variable heat flux on buckling of carbon nanotubes using non-equilibrium molecular dynamics simulation

It is critical to know the buckling behavior of carbon nanotubes under non-uniform heat flux for maintaining stability in thermal applications at the nanoscale. In this study, time-dependent external heat fluxes of 1, 3, 5, and 10 W/m² are applied to carbon nanotubes using non-equilibrium molecular dynamics simulations, and the resulting structural and energetic responses are analyzed systematically. The findings demonstrate that, in parallel with the evolution towards the post-buckling state, some kinetic energy and mean squared displacement increased during simulation before abruptly decreasing and stabilizing. Before buckling, potential energy peaked and then dropped to negative values, indicating structural relaxation. The center of mass displacement was constrained, and the interaction energy stabilized at 3.63×10¹³ eV, reflecting the structure's stability following buckling. Additionally, kinetic energy increased from about 50 eV to 130–140 eV and then decreased to 80–90 eV after buckling when the heat flux increased from 3 to 10 W/m². With a slight increase in atom mobility, mean squared displacement went from 0.41 to 0.412. After initially reaching its maximum, potential energy began to gradually decline, with the decline being greater at higher heat flux values. The interaction energy increased at 2.25 × 10⁻¹² eV at 3 W/m² and then decreased at 3.75 × 10⁻¹⁴ eV at 10 W/m², indicating that higher thermal energy generates higher molecular motion and structural relaxation, stabilizing the buckled shape. The center of mass displacement decreased with increasing heat flux, suggesting greater local deformation and less overall movement. The originality of this work lies in simulating an actual, spatially non-uniform heat flux and examining its direct effect on carbon nanotubes' thermomechanical behavior, a situation overwhelmingly unexplored by the literature. The results offer useful guidance for the design of carbon nanotube-based systems in nanoelectronics and thermal management systems operating under non-uniform thermal conditions.

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