where _ Q is an arbitrary elemental property, J ` is the molar content of element b in the material, and b runs over all c elements in the composition. For the three-component materials, c = 3. We note that oxygen is also present in all materials, but its proportion is not known from the catalysts formulation nor measured for all materials. Therefore, the oxygen content is not included in the material's characterization. Properties that can be readily calculated for the free atom are advantageous to structure-based properties because they do not have to be reevaluated for each new material. In total, 11 descriptive parameters are used in our SGD analysis: