1994/05/16 by Kikuo Harigaya
Chemistry · Materials Science · Physics and Astronomy · #Carbon Nanotubes in Composites #Fullerene Chemistry and Applications #Graphene research and applications #chem-ph #cond-mat
paper · pdf · doi:10.1103/physrevb.50.17606
published as Phys. Rev. B 50 (1994) 17606-17610 · Note: A full preprint with figures should be requested to the author. It will be sent by air-mail.; E-mail: [email protected]
arxiv created 1994/05/16 · openalex publication_date 1994/12/15 · arxiv updated 2009/11/30 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/28
We theoretically investigate optical-absorption spectra of C60^6\mathrm\ensuremath- and C70^6\mathrm\ensuremath-, and discuss relations with the optical properties of alkali-metal-doped fullerides A6C60 and A6C70. This is a valid approach for systems where molecular-exciton (Frenkel-exciton) effects are dominant. We use a tight-binding model with long-ranged Coulomb interactions and bond disorder. Optical spectra are obtained by the Hartree-Fock approximation and the configuration interaction method. We find that the Coulomb interaction parameters, which are relevant to the optical spectra of A6C60 (A6C70) in order to explain the excitation energies and relative oscillator strengths of absorption peaks, are almost half of those of the neutral C60 (C70). The reduction of the effective Coulomb interactions is concluded for the heavily doped case of C60 and C70. This finding is closely related to the experimental fact that dielectric constants of fullerides, which are maximumly doped with alkali metals, become about twice as large as those of the neutral systems.