The degenerate Fermi gas of $\pi$ electrons in fullerenes and the $\sigma$ surface instabilities

TL;DR

This paper investigates how pi electron degeneracy pressure influences the stability and surface instabilities of fullerenes with various symmetries and sizes, highlighting conditions under which it stabilizes or destabilizes the structures.

Contribution

It introduces a model treating pi electrons as a degenerate Fermi gas to analyze their impact on fullerene surface stability across a wide size range.

Findings

Degeneracy pressures can enhance or stabilize fullerene surface instabilities.

Pi electron degeneracy effects vary with fullerene size and symmetry.

The model applies to fullerenes from C20 to C1500.

Abstract

The departure from perfect spherical symmetry in the case of fullerenes, C60 being the sole exception, induces instabilities due to the stresses generated by the pentagonal protrusions in the sigma-bonded surfaces. By assuming sigma and pi separability and treating pi electrons as a degenerate Fermi gas in the two shells around the central sigma structure, the resulting degeneracy pressures can further enhance the sigma-surface initiated instabilities for non-icosahedral structures especially for those smaller than C60 as well as the icosahedral fullerenes that are larger than C60, with large protrusions. Under certain circumstances the net degeneracy pressure across the sigma surface might have structure-stabilizing effect. The role of the pi electron degeneracy in a broad range of fullerenes from C20 to C1500 and its effects on fullerene stability is investigated.