Nano-molecular springs: How high will it jump?

When pressed vertically against the surface, a spring, in the present case a polyyne rod, will buckle. Upon release, it will be propelled from the surface. The complete conversion of 10kcal/mol of potential energy, stored in a C₁₀ spring, into kinetic energy, will propel the rod to a height of 35km. However, part of the potential energy will be lost to non-productive vibrations and rotations. The present molecular dynamics study is aimed to find the dependence of the efficiency of potential to translational energy conversion on various physical parameters. It is found that in general the energy fraction available for propulsion decreases with the length of the rod and for C₁₀ the efficiency converges to values around 0.5±0.1 at high initial potential energies. The effect of other parameters such as the binding energy to the surface and corrugation was also investigated. We suggest that our observations could be explained on the basis of interplay between the two detachment mechanisms - 'push' and 'pull'.