Notice how the gained BEP relation is good with a regression coefficient R of 0.899, even if mixing different surface terminations crystallographic structures, and reaction mechanisms, see Fig. , and as good as a descriptor as the εd, shown in Fig. , underscoring that εd is, perchance, a suited descriptor of the TMs surfaces chemical activity, and, in an indirect way, of the chemical reactivity, as ΔE does. Aside, the BEP slope of 0.667 is in between the limits of 0 and 1, implying that is not simply defined by ΔE, but also other TM surface factors play a role in the TS definition and the estimate of the Ea.