The variation for the free energy of the global minima found for each stoichiometry at different chemical potentials of the molecular oxygen reservoir is evaluated by means of AITD as described in the methods and computational details section. The Gibbs free energy of formation (ΔGf) at each value of the chemical potential of the molecular oxygen reservoir (μO) for the global minimum of each stoichiometry is determined by equation Common to all systems, higher values of μO (corresponding to oxidizing environments) increase the stability of stoichiometries with a higher oxidation state, a direct consequence of the thermodynamic equilibrium with a molecular oxygen reservoir from which it is easier to extract O from (i.e. with a higher chemical potential to react).