Exploring Adjacent Pentagons in Non-IPR and SW Defective Si60 and Si70 Silicon Fullerenes: a Computational Study

Abstract

We have applied DFT calculations to investigate the effect of the adjacent pentagons (APs) on the geometries, stabilities, and electronic structures of the non-IPR isomers of Si60 and Si70 fullerenes containing three adjacent pentagon pairs, Si60(D3) and Si70(C2v), and the SW defective Si60 and Si70 fullerenes with four AP pairs. These non-IPR isomers of Si60 and Si70 cages are more stable than their IPR ones. Natural bond orbital analyses and electrostatic potential surfaces indicate the charge densities are more localized at the pentagon-pentagon edges of the non-IPR fullerenes, which increase by going to the charged ones. Based on our results, the SW rearrangement process in the Si60 and Si70 silicon fullerenes is exothermic. A silylene-like transition state along a stepwise reaction path is characterized at the B3LYP/6-311 + G* level of theory. The barrier for the SW rearrangement of Si60 fullerene is obtained to be 5.36 eV which is smaller than that reported for SW rearrangement of C60 fullerene.