Fusion mechanism in fullerene-fullerene collisions -- The deciding role of giant oblate-prolate motion

TL;DR

This study explains the unusually high fusion barriers and small cross sections in fullerene-fullerene collisions by identifying the dominant role of a giant oblate-prolate vibrational mode, supported by quantum dynamics and a macroscopic model.

Contribution

The paper introduces a microscopic quantum model and a macroscopic collision model that accurately predict fusion barriers and elucidate the role of specific vibrational modes in fullerene fusion.

Findings

Giant oblate-prolate H_g(1) mode excitation is key to fusion behavior.

The macroscopic model reproduces quantum molecular dynamics results.

Predicted fusion barriers match experimental data.

Abstract

We provide answers to long-lasting questions in the puzzling behavior of fullerene-fullerene fusion: Why are the fusion barriers so exceptionally high and the fusion cross sections so extremely small? An ab initio nonadiabatic quantum molecular dynamics (NA-QMD) analysis of C$_{60}$+C$_{60}$ collisions reveals that the dominant excitation of an exceptionally "giant" oblate-prolate H$_g(1)$ mode plays the key role in answering both questions. From these microscopic calculations, a macroscopic collision model is derived, which reproduces the NA-QMD results. Moreover, it predicts analytically fusion barriers for different fullerene-fullerene combinations in excellent agreement with experiments.