Fig. 4: Free energy profiles for N2O5 hydrolysis in liquid water via the ionic or stepwise ionic mechanisms.

Free energy profiles for N2O5 hydrolysis at the air–water interface (orange line) or in the bulk water (blue line) via the ionic (a) or stepwise ionic (b) mechanisms. Energy barriers are presented in kcal mol−1. The standard deviation of the free energy of the final 8 ps of the MetaD biased QM/MM simulations is used to determine the error bars. The blue and orange shading in the background of (b) indicates the first and second steps, respectively, in the free energy profile for hydrolysis via stepwise ionic mechanism.