Can two H2 molecules be inserted into C60 – an accurate first-principles exploration of structural, energetic and vibrational properties of the 2H2@C60 complex

Encapsulation of Hydrogen Molecules in C50 Fullerene: An ab Initio Study of Structural, Energetic, and Electronic Properties of H2@C50 and 2H2@C50 Complexes

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 H2 molecules that can be encapsulated inside a C50 cage. It is demonstrated that the 2H2@C50 complex is thermodynamically unstable based on its positive complexation energy. Some discrepancies, however, were found with respect to the stability of the H2@C50 complex. Indeed, SVWN5, PBEPBE, MP2, B2PLYP, and B2PLYPD calculations confirmed that the H2@C50 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 H2 molecule can indeed be encapsulated inside the C50 cage. Other factors, such as the host-guest interactions and bond dissociation energy, were analyzed and discussed.