Analysis of different techniques for modelling excitons in carbon nanotubes

It is now widely accepted that exciton effects play an important role in the optical processes of carbon nanotubes. However, previous theoretical work has tended to concentrate on an understanding of exciton binding energies, with little attention paid to calculations of exciton sizes. In this work we employ two approaches: a k·p model and a variational technique, and we examine their ability to make simultaneous predictions of exciton binding energy and size, while comparing our results to previous work taken from the literature.