▎ 摘　　要

A description of the electronic properties of model zigzag carbon nanotubes (CNTs) and chiral-edge graphene nanoribbon using a computational method for accelerating first-principles Green function calculations is presented. This approach utilizes an optimal basis set for representing the polarization propagator lowering the computational cost without loss of accuracy. The electronic structures and the equilibrium geometries were obtained within the pseudopotential implementation of ab initio total energy density functional theory. Accurate calculations to determine quasiparticle excitations in carbon nanostructures, notably electronic band gap, are performed in the framework of GW treatment of self-energy. The obtained results on band gaps for (7,0), (8,0) CNTs at Gamma point and calculations on (4,2) nanoribbon with edge irregularities show the potential of this method to perform accurate calculations on large carbon-based systems of technological interest and structures with localized defects, otherwise difficult to address with conventional approaches. This method, recently implemented by Umari et at. [Umari et al., Phys. Rev. B 79, 201104 (2009)], may be used as a predictive tool of spectral properties, excited states and optical response in extended systems. (C) 2009 WILEY-VCH Vertag GmbH & Co. KGaA, Weinheim