First-principles study on atomic configuration of electron-beam irradiated C$_{60}$ clusters

TL;DR

This study uses first-principles calculations to explore how electron-beam irradiation alters the atomic and electronic structure of C60 clusters, revealing transitions from semiconducting to metallic states due to specific bonding rearrangements.

Contribution

It provides a detailed theoretical model of the atomic configurations and electronic properties of irradiated C60 clusters, highlighting the transition mechanisms between different bonding structures.

Findings

Rhombohedral C60 polymer is a semiconductor with a narrow band gap.

Rearrangement to sp2 bonds induces metallic behavior.

Conductance spectra are affected by bond reorganization.

Abstract

A theoretical study proposes the atomic configuration of electron-beam irradiated C$_{60}$ thin films. We examined the electronic structure and electron-transport properties of the C$_{60}$ clusters using density-functional calculations and found that a rhombohedral C$_{60}$ polymer with $sp^3$-bonded dumbbell-shaped connections at the molecule junction is a semiconductor with a narrow band gap while the polymer changes to exhibit metallic behavior by forming $sp^2$-bonded peanut-shaped connections. Conductance below the Fermi level increases and the peak of the conductance spectrum arising from the $t_{u1}$ states of a C$_{60}$ molecule becomes obscure after the connections are rearranged. The present rohmbohedral film, including the [2+2] four-membered rings and peanut-shaped connections, is a candidate to represent the structure of the metallic C$_{60}$ polymer at the initial stage of electron-beam irradiation.