Energy Decomposition along Reaction Coordinate and Energy Weighted Reactive Flux: 1. Theory

Abstract: A theoretical framework is proposed for an energy decomposition scheme along the reaction coordinate, in which the ensemble average of the potential energy weighted with reactive flux intensity is decomposed into energy components at the per-coordinate level. The decomposed energy quantity is demonstrated to be closely related to the free energy along the reaction coordinate and its connection to the emergent potential energy is provided. We also explore the property of the reactive flux weighted by the potential energy in the subspace of collective variables. A free energy analogue is then proposed in the subspace of collective variables and the directional derivative of this free energy analogue in the direction of the reactive flux is shown to be useful in the identification of the reaction coordinate and the minimum free energy path.