Ab initio HF and density functional theory studies of C60@Si60

Ab initio HF and DFT calculations on C-60@Si-60 confirmed our previous semiempirical results that the interaction of two fullerene layers brings about extensive modification of the bond parameters, the C-C, Si-Si and Si-C bond distances being close to the respective single bond lengths. However, the present calculations revised the previous HOMO-LUMO picuture and the stability relations among C-60@Si-60, C-60 and Si-60 species.