Geometry-induced smoothing of van Hove singularities in capped carbon nanotubes

TL;DR

This paper investigates how the geometry of capped carbon nanotubes influences their electronic density of states, revealing a smoothing of van Hove singularities through a combined theoretical and numerical approach.

Contribution

It introduces a unified gauge field-theory model for both nanotube and cap regions, demonstrating the smoothing effect on van Hove singularities analytically and numerically.

Findings

Van Hove singularities are smoothed in capped nanotubes.

The model applies to both metallic and semiconducting nanotubes.

Comparison with experiments supports the theoretical results.

Abstract

The electronic states of capped semi-infinite nanotubes are studied within the phenomenological gauge field-theory model. A single manifold for the description of both the nanotube and the cap region (considered as nearly a half of either Ih or I fullerene) is suggested. The wavefunctions and the density of states (DoS) are numerically calculated for both metallic and semiconducting nanotubes. The smoothing of van Hove singularities is found and proven analytically. The comparison with the experimental observations is discussed.