Electronic structure and cohesive energy of silylmethyl fullerene and methanoindene fullerene solids

Abstract

Using the density functional theory, we studied the energetics and electronic structures of chemically decorated fullerene solids, monoclinic phases of silylmethyl fullerene (SIMEF) and methanoindene fullerene (MIF), under the experimentally determined lattice parameters. Cohesive energies of these solids are 1.83 and 1.07 eV for SIMEF and MIF, respectively, despite the large intermolecular spacing owing to the functional groups. The SIMEF and MIF solids are semiconductors with a moderate band gap of about 1.2 eV with narrow dispersion band near the band gap. We also elucidated that these solids exhibit a strong anisotropic band dispersion relation near the gap, because of their large asymmetric molecular shape. The calculated electron effective masses range from 1.37me to 7.91me for the SIMEF solid and from 0.57me to 4.23me for the MIF solid.