Dimerization structures on the metallic and semiconducting fullerene tubules with half-filled electrons

TL;DR

This study investigates possible dimerization patterns and electronic structures in fullerene tubules using an extended Su-Schrieffer-Heeger model, revealing conditions for metallic or semiconducting behavior based on lattice geometry and energy gaps.

Contribution

It introduces a comprehensive analysis of dimerization patterns in fullerene tubules considering various geometries and their electronic properties at half-filling.

Findings

Kekule structures are likely in gapless undimerized systems.

Large-gap systems favor chain-like distortions with semiconducting properties.

Electronic gaps can reach up to room temperature energy scales.

Abstract

Possible dimerization patterns and electronic structures in fullerene tubules as the one-dimensional pi-conjugated systems are studied with the extended Su-Schrieffer-Heeger model. We assume various lattice geometries, including helical and nonhelical tubules. The model is solved for the half-filling case of $\pi$-electrons. (1) When the undimerized systems do not have a gap, the Kekule structures prone to occur. The energy gap is of the order of the room temperatures at most and metallic properties would be expected. (2) If the undimerized systems have a large gap (about 1eV), the most stable structures are the chain-like distortions where the direction of the arranged trans-polyacetylene chains is along almost the tubular axis. The electronic structures are ofsemiconductors due to the large gap.