Directional control of surface rolling molecules exploiting non-uniform heat-induced substrates

Abstract

Molecular machines, such as nanocars, have shown promising potential for various tasks, including manipulation at the nanoscale. In this paper, we examined the influence of temperature gradients on nanocar and nanotruck motion as well as C₆₀ – as their wheel – on a flat gold surface under various conditions. We also compared the accuracy and computational cost of two different approaches for generating the temperature gradient. The results show that severe vibrations and frequent impacts of gold atoms at high temperatures increase the average distance of C₆₀ from the substrate, reducing its binding energy. Moreover, the temperature field drives C₆₀ to move along the temperature variation; still, the diffusive motion of C₆₀ remained unchanged in the direction perpendicular to the temperature gradient. Increasing the magnitude of the temperature gradient speeds up its motion parallel to the gradient, while raising the average temperature of the substrate increases the diffusion coefficient in all directions. The temperature field influences the nanocar motion in the same manner as C₆₀. However, the nanocars have a substantially shorter motion range compared to C₆₀. The relatively larger, heavier, and more flexible chassis of the nanocar makes it more sluggish than the nanotruck. In general, the motion of large and heavy surface rolling molecules is less affected by the temperature field compared to small and light molecules. The results of the study show that concentrated heat sources can be employed to push surface rolling molecules or break down their large clusters. We can exploit a temperature field as a driving force to push nanocars in a desired direction on prebuilt pathways.