Exciton bandstructure in carbon nanotubes from many-body perturbation theory*

Understanding exciton decay processes and lifetimes in solid-state materials is of great interest, with emerging applications such as material characterization and energy conversion and storage. A predictive theoretical assessment of the involved underlying interaction mechanisms is, however, highly challenging. A computational scheme that supplies reliable excited-state properties in crystals is many-body perturbation theory within the GW approximation and the Bethe-Salpeter equation (BSE) approach (GW-BSE). This method allows a predictive evaluation of exciton wavefunctions and excitation energies, and recently also exciton bandstructures. In this study, we explore the excitonic bandstructure of a quasi 1D system – single wall carbon nanotubes (SWCNTs), a well-examined material due to its unique electronic properties and application in optoelectronic devices. We further explore the relation of the exciton dispersion to excitonic decay processes.