Fig. 3: Free energy profiles for the reaction of N2O5 with water monomer in liquid water via molecular mechanisms.

Free energy profiles for the reaction of N2O5 with water monomer via the molecular mechanism in the gas phase (green line), at the air–water interface (orange line), or in the bulk water (blue line). During the reaction, the H group of H2O can attach to the terminal (a) or central oxygen atom (b) of O2NONO2. 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.