Second, within predictive-quality multiscale modeling, its rate constant needs to be computed from first-principles. Presently, for heterogeneous catalysts this is typically performed at the level of density-functional theory (DFT) and (harmonic) transition state theory. While this simplifies the task to the determination of the activation barrier aka transition state (TS) on the potential energy surface (PES), it still comes at a certain computational cost. For these reasons, existing microkinetic models for surface catalysis typically consider only a minimum number of elementary processes, which are hand-selected by the human researcher, and thus primarily focus on more intuitive surface reaction steps.