Electronic and optical properties of the Vanderbilt-Tersoff model of negative-curvature fullerene

The electronic structure and the optical properties of a model of negative-curvature fullerene suggested by Vanderbilt and Tersoff are studied by detailed first-principles local-density calculations. It is shown that this hypothetical material is a semiconductor with an indirect band gap of 0.48 eV and a large ratio of electron-hole effective masses. The optical properties are very different from those of graphite or ${\mathrm{C}}_{60}$ fullerene.