Reactive path ensembles within nonequilibrium steady-states

Rare reactive events encapsulate a range of phenomena relevant to chemical and statistical physics. While their study has been simplified through decades of computational and theoretical work, the field is predominantly informed by systems in thermodynamic equilibrium. We present our work in which we apply variational path sampling to systems in nonequilibrium steady states to elaborately characterize how nonequilibrium driving can inherently change the mechanism of reactive processes in a way that cannot be rationalized through concepts within equilibrium statistical mechanics. For instance, we study the shear-induced folding and unfolding transition of a polymer to illustrate how the quintessential notion of reactive processes as barrier-crossing events is insufficient out of equilibrium, due to the emergence of currents that can couple to the reactive mode and enhance or gate reactions. Similarly, we consider conformational changes of an object in an active bath to delineate how activity can open up new pathways and accelerate kinetics. We believe this work will lead towards a unified understanding of the broad class of reactive phenomena that occur out of equilibrium.