Strong Correlation Effects in the Fullerene C20

TL;DR

This paper investigates the electronic, magnetic, and structural properties of the smallest fullerene, C20, using advanced computational methods to understand the effects of strong electron correlations and phase transitions.

Contribution

It provides a comprehensive analysis of C20's properties with new insights into correlation effects, metal-insulator transition, and Jahn-Teller phenomena using exact diagonalization and quantum Monte Carlo methods.

Findings

Evidence for a metal-insulator transition at U ~ 4t.

Strong correlations significantly influence C20's magnetic and spectral properties.

Insights into the role of correlations in Jahn-Teller effects in C20.

Abstract

The smallest fullerene, dodecahedral C20, is studied using a one band Hubbard model parameterized by U/t. Results are obtained using exact diagonalization of matrices with linear dimensions as large as 5.7 x 10^9, supplemented by quantum Monte Carlo. We report the magnetic and spectral properties of C20 as a function of U/t and investigate electronic pair binding. Solid forms of C20 are studied using cluster perturbation theory and evidence is found for a metal-insulator transition at U ~ 4t. We also investigate the relevance of strong correlations to the Jahn-Teller effect in C20.