As the discussion below involves nuances among various types of enthalpies that can be quite confusing, we decide to adopt a new set of notations to assist understanding. Specifically, we use ∆ X Y H • Z , where X denotes the source of data ("qm" for ab initio calculation, "ref" for accurate reference values, "bac" for BAC-corrected values, "aec" for AEC-corrected values, "iso" for values corrected by isodesmic reaction approach), Y denotes the type of enthalpy ("f" for formation, "rxn" for reaction), Z denotes which species the enthalpy represents ("t" for target species, "i" for reference species in isodesmic reaction), and finally, • denotes standard state at 298 K. For example, ∆ qm f H • t represents the heat of formation for target species at 298 K calculated from QM.