The separation energy of two nanograins: Results from atomistic simulations

Abstract

The separation energy of two grains is an important quantity in studies of granular aggregates. It gives the energy needed to separate two grains from each other and is relevant for studies of grain and aggregate collisions as it determines grain sticking and bouncing. Using molecular dynamics simulations for a model system consisting of atoms interacting via the Lennard-Jones potential, we investigate to what extent available macroscopic laws for the separation energy can be founded in atomistics. We verify the predicted dependence of the separation energy on the surface energy. The dependence on grain radius is steeper in atomistic simulations than predicted by macroscopic laws. This can be rationalized by increased energy dissipation during the separation process for smaller grains. These results may be relevant in theoretical studies of the evolution of dust clouds by collisions.