Structures and stabilities of endohedral fullerenes: X@C24H24 (XÂ =Â H, Li, Li+, Na, Na+, K, K+, Be, Mg, Mg2+, Ca, Ca2+, B, Al, C, Si, N and P)

Based on the D6d-symmetrical C24H24 fullerene, the equilibrium geometries, electronic structures, vibrational frequencies, energy gaps and BSSE-corrected binding energies of the endohedral fullerenes X@C24H24 (X = H, Li, Li+, Na, Na+, K, K+, Be, Mg, Mg2+, Ca, Ca2+, B, Al, C, Si, N and P) have been calculated using the DFT-B3LYP/6-31G(d) level. The results suggest that all the endohedral fullerenes are slightly enlarged along the same groups, such as IA, IIA, IIIA, IVA and VA, respectively. The endohedral fullerenes containing C, Si, N and P atoms have their high-spin states, and containing Li+, Mg2+ and Ca2+ cations are energetically favorable. Additionally, some of the investigated compounds have high energy gap, but they are unlikely to show high thermodynamic stability because of the positive BSSE-corrected binding energies.