Origin of rebounds with a restitution coefficient larger than unity in nanocluster collisions.

We numerically investigate the mechanism of super rebounds (rebounds in which the restitution coefficient is larger than unity) for head-on collisions between nanoclusters. It is confirmed that the temperature and the entropy of the nanocluters decrease after the super rebounds by our molecular dynamics simulations. It is also found that the initial metastable structure plays a key role for the emergence of the super rebounds.