To explicitly account for the effects carried by partial solvation on the DA reaction, we performed Born-Oppenheimer AIMD simulations combined with a well-tempered MetD approach using the CP2K package. Simulations started from the reactant complex (RC) state, and aimed at determining the free-energy barriers of the reaction in the gas phase, at the air-water interface, and in the bulk. As for the simulation in the gas phase and in the bulk, the cubic box size was 12 Å × 12 Å × 12 Å. The bulk model includes 52 water molecules and one reactant (i.e., CPD+ALT). As far as the AIMD+MetD simulations of the water interface are concerned, water slabs containing up to 200 water molecules were constructed (Figure ).