Computational evidence for the possible existence of the open heterofullerenes C56X2Y (X = N, P; Y = O, S) and C60−6kN4k

Based on calculations using density functional theory, we proposed a series of open heterofullerenes: C56N2O, C56N2S, C56P2O, and C56P2S, which constitute the first examples of open heterofullerenes not externally functionalized. They exhibit large HOMO–LUMO gaps which are comparable to that for C60. The Fermi level of the system becomes higher as the heterofullerene changes from C56N2O to C56P2S. In the solid-state, face centered cubic structures are more stable than body centered cubic for all of them. In addition, we have also investigated other heterofullerenes with empty sites (=C54N4 and C48N8).