The band structure of a single-bonded cubic phase of nitrogen has been investigated by the ab initio calculations of the pseudopotential density functional method. The basic optical constants including the dielectric function, the refractive index, the absorption, the electron energy-loss spectrum, the optical conductivity and the reflectivity of the single-bond cubic nitrogen and their dispersion properties were calculated. These theoretical results suggested that the single-bond cubic nitrogen could be a wide-gap optical material with unique properties. (c) 2005 Elsevier B.V. All rights reserved.