The NaCl system was built in a similar setting to an earlier study by Wolf and Stock . The ion parameters were obtained from the Amber ff99 parameters . NaCl was solvated in a cubic periodic box (0.3 × 0.3 × 0.3 nm 3 ) filled with TIP3P water molecules 36 (Figure ). Afterward, the Na-Cl distance 𝑑 !"#$ was energetically minimized (0.261 nm). The distance was constrained during the next constant pressure and constant temperature (NPT) equilibration step (100 ps) at 300 K and 1 atm. Thereafter, CF-SMD simulations were executed for several values of a constant force (Table ). The constant force was applied to the Na and Cl ions along the Na-Cl distance. The dissociation time τ(𝐹) under a constant force 𝐹 was defined as the first time that the Na-Cl distance was greater than a threshold (Table ). As a reference, an unbiased MD simulation at 300 K was performed up to 1 µs, producing a free-energy profile of the distance: 𝐺(𝑑 !"#$ ) = -𝑘 % 𝑇 ln 𝑃(𝑑 !"#$ ), where 𝑃(𝑑 !"#$ ) denotes the probability density of the distance 𝑑 !"#$ .