A second application of the automated quantum chemistry-based workflow is the ability to predict the reactivity of covalent inhibitors. In the work of Hermann et al. , calculated activation energies of different warheads reacting with CH 3 S -were used to estimate the reactivity towards cysteine. As a faster alternative, they also showed that a warhead-associated electrophilicity index could be used to predict the reactivity of some warhead classes. The electrophilicity index (ω) is defined as