Derivation of the screened Bloch equations and application to carbon nanostructures

► Microscopic derivation of momentum-dependent dielectric screening. ► Screening is crucial to understand optical properties of nanotubes. ► Efficient screening in metallic tubes due to crossing bands. ► Their excitonic binding energy is still around 50 meV. ► Presented method is not limited to nanotubes, but can be applied to arbitrary nanostructures including graphene and nanoribbons.