Conventional and density-fitting local Møller-Plesset theory calculations of C60 and its endohedral H2@C60 and 2H2@C60 complexes

► DF-LMP2 method is applied for C60 and nH2@C60 (n = 1, 2). ► H2@C60 is a thermodynamically stable complex whereas 2H2@C60 is unstable. ► cc-pVTZ basis set is required to obtain accurate DF-LMP2 complexation energies. ► BSSE is insignificant in the DF-LMP2/cc-pVTZ determination of complexation energies. ► H2@C60 exhibits a slight elongation of the HH bond leading to a red shift in ν(HH).