Note that this is a collective quantity between reaction coordinate R 0 and the solvent DOF Q j . For the solventsolute interactions in Eq. 2, with an increasing number of solvent molecules, the outer sphere solvents will only be weakly coupled to the solute, while the inner sphere solvent strongly coupled to the solute, resulting in a solutesolvent distance-specific coupling strength C j . In this study, we keep Λ as a fixed parameter.