Ab initio study of silicon-multisubstituted neutral and charged fullerenes- art. no. 085411

The electronic and structural properties of Si-doped fullerenes, obtained f rom C-60 by replacing up to 12 C atoms with Si atoms, are studied by means of first-principles density-functional theory calculations using numerical atomic orbitals as basis sets. We have analyzed the relative stability of s everal C60-xSix isomers, with x=1, 2, 3, 6, and 12. We find that, for x=3 a nd 6, the Si atoms strongly "prefer'' to be first neighbors of each other, in order to minimize the number of SI-C bonds. However, these configuration s of lower energy present a few relatively weak Si-C and Si-Si bonds that c ould indicate possible breaking paths. For a better comparison with the exp erimental measurements, we have also considered some positively charged ion s, and report the differences between properties of these ions and the corr esponding neutral molecules.