Theoretical study of highly doped heterofullerenes evolved from the smallest fullerene cage

The structural stabilities and electronic properties of C ₁₂X ₈ heterofullerenes where X = B, Al, Ga, C, Si, Ge, N, P, and As are probed at the MP2/6-311+G*//B3LYP/6-31+G* level of theory. Vibrational frequency calculations show that all the systems are true minima. Probing the geometries show the contraction of C=C double bonds to compensate for the longer C-X bonds. The calculated binding energies of C ₁₂P ₈ and C ₁₂B ₈, 5.93 and 5.81 eV/atom, respectively, show them the most stable heterofullerenes of all. While Si, Ge, Al, and Ga doping increase the conductivity of fullerene through decreasing its HOMO-LUMO gap, B, N, P, and As doping enhance its stability against electronic excitations via increasing the gap. High charge transfer on the surfaces of our stable heterofullerenes, especially C ₁₂Al ₈, C ₁₂Si ₈, and C ₁₂Ga ₈, provokes further investigations on their possible application for hydrogen storage.