Exohedral Silicon Fullerenes: Si60Pn60 and Si80Pn60 (Pn = P, As, Sb and Bi)

Abstract

Based on density functional theory (DFT) calculations, we predict that the icosahedral structures of the silicon fullerenes Si60 and Si80 can be stabilized by 12 exohedral pentagons of group V-A unit Pn5 (Pn = P, As, Sb or Bi). The 12 pentagons can fully passivate the dangling bonds associated with 12 pentagonal Si5 rings on the silicon fullerene cages, thereby resulting in stable exohedral silicon fullerenes Si60Pn60 and Si80Pn60. Properties of the eight Si60Pn60 and Si80Pn60 clusters, including harmonic vibrational frequencies, electron affinity (EA), the HOMO–LUMO gap and NICS values, are computed. We find that all eight Si60Pn60 and Si80Pn60 fullerenes possess relatively large HOMO–LUMO gaps, high electron affinities, and that the Si60Pn60 fullerenes exhibit weak aromaticity. Among eight clusters examined, the exohedral fullerene Ih-Si60P60 possesses the largest cohesive energy per atom. Ab initio molecular dynamics (AIMD) simulation is performed to demonstrate thermal stability of the hollow cage structure of Si60P60 at the room temperature.