  Impact phenomena of small clusters subject to thermal fluctuations are
numerically investigated. From the molecular dynamics simulation for colliding
two identical clusters, it is found that the restitution coefficient for
head-on collisions can exceed unity when the colliding speed is smaller than
the thermal velocity of one ``atom'' of the clusters. The averaged behavior can
be understood by the quasi-static theory of impact phenomena. It is also
confirmed that our result is governed by the fluctuation theorem.
