The approaches can be classified according to their use of an atomic reference basis sets or molecular fragment reference basis sets. In an atomic reference basis set method, every element must be assigned a single reference species (typically a closedshell gas-phase molecule), which can be abstracted into elemental chemical potentials. The atomic reference basis set methods always conserve the reaction enthalpies as if they were calculated from the plain DFT energies, so long as correction factors are not applied and data from different sources are not mixed together. Conserving all DFT reaction enthalpies does not reproduce the thermodynamics of the overall gas-phase reaction from the accurate gas-phase ∆ f H of global thermochemical networks like the ATcT. Therefore, correction factors are applied to DFT energies to reduce discrepancies by adjusting adsorption enthalpies. However, the only method to ensure an exact agreement is to integrate the DFT data into the global thermochemical networks by anchoring it to the gas-phase or adsorbates ∆ f H of the references.