Encapsulation of Hydrogen Molecules in C(50) Fullerene: An ab Initio Study of Structural, Energetic, and Electronic Properties of H(2)@C(50) and 2H(2)@C(50) Complexes

[Image: see text] Various DFT functionals, including those containing long-range interactions and dispersion, together with HF and MP2 theoretical methods, were used to identify the number of H(2) molecules that can be encapsulated inside a C(50) cage. It is demonstrated that the 2H(2)@C(50) complex is thermodynamically unstable based on its positive complexation energy. Some discrepancies, however, were found with respect to the stability of the H(2)@C(50) complex. Indeed, SVWN5, PBEPBE, MP2, B2PLYP, and B2PLYPD calculations confirmed that the H(2)@C(50) complex is thermodynamically stable, while HF, BP86, B3LYP, BHandHLYP, LC–wPBE, CAM–B3LYP, and wB97XD showed that this complex is thermodynamically unstable. Nevertheless, examination of strain and dispersion energies further supported the fact that one H(2) molecule can indeed be encapsulated inside the C(50) cage. Other factors, such as the host–guest interactions and bond dissociation energy, were analyzed and discussed.