Super-elastic collisions in a thermally activated system

TL;DR

This study investigates impact phenomena of thermally fluctuating clusters, revealing super-elastic collisions with restitution coefficients exceeding unity at low speeds, explained by quasi-static theory and governed by the fluctuation theorem.

Contribution

It demonstrates super-elastic collisions in thermally activated clusters and links the findings to the fluctuation theorem, providing new insights into impact behavior at microscopic scales.

Findings

Restitution coefficient can exceed unity at low colliding speeds.

Behavior aligns with quasi-static impact theory.

Results are governed by the fluctuation theorem.

Abstract

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.