For simplicity, we assume throughout this work that DFT energies E i have already been zero-point corrected, and we assume a temperature of 0 K so that the finite-temperature correction can be neglected. The quantity H i (T, p) does not have a ∆ as it is not an enthalpy of formation defined in a formation reaction; instead, it is defined based on the relative energies of the (valence) electrons. It is often more common in the catalysis literature to work with the Gibbs free energy G(T, p), which is similarly defined as: