A DFT study on the structural and electronic properties of Td and C2 symmetry C24X4 and C22X6 heterofullerenes (X = B, Al, N, and P)

DFT calculations are applied to compare and contrast heteroatom doped Td and C2 symmetry C24X4 and C22X6 (X = B, Al, N, and P) heterofullerenes. Vibrational frequency analysis confirms that all of the systems are true minima. Probing the geometries show the alteration of CC double bonds to accommodate heteroatoms in the fullerene cage. The calculated binding energies of 6.54 and 6.39 eV/atom for C24N4 and C22N6, respectively, reveal them as the most stable heterofullerenes. Evaluating nucleus independent chemical shifts at the cage centers clearly show the high aromatic character of N-doped fullerenes (−29.33 and −24.16 ppm compared to +2.09 for the sole carbon cage).