Figure shows a snapshot of the AIMD simulation of the RC at the air-water interface and Figure shows the water density profile. The electrostatic potential generated by the Mulliken charges of the water molecules within the interfacial region on RC has been calculated. Specifically, we consider the solvent EF, F, calculated at the C1 atom position of RC and oriented along the Z-axis (i.e., reaction axis). The direction of such a Cartesian component is defined in the same way as in Figure , so that a positive value promotes the DA reaction. Computing details are provided in the Supporting Information. Figure depicts that the IEF generated by interfacial water molecules along the reaction axis fluctuates between -0.2 and 0.2 V/Å, with the majority falling within the range of -0.1 to 0.1 V/Å. It is noteworthy that also additional simulations without fixing the RC were performed, leading to similar results (Figure ). The dynamic nature of the air-water interface and the fluctuating character of the IEF was previously reported also by the M. F. Ruiz-López group where they used an OH radical as a probe, 105 as well as the T. Head-Gordon group where the IEF was projected onto the O-H bond of a water molecule. According to the 50-ps-long AIMD simulation we report in this work, the resulting time average of the IEF is -0.007 ± 0.0002 V/Å. If we plug this value into the formula ΔΔG ‡ = -ΔμZ,0 ‡ FZ, and let the value of ΔμZ,0 to be 3.1 D, which is the average of the DFT value calculated above in the gas phase (2.62 D) and in aqueous phase (3.57 D, implicit solvent model), it leads to a barrier increase of only ~ 0.02 kcal/mol. Based on this small average value, one might be tempted to conclude that the electrostatic solvation effects on chemical reactivity are negligible. This, however, should be interpreted with caution because the average value masks the potential role of fluctuations and dynamical effects. Local IEF may have chances to catalyze the reaction when properly oriented along the reaction axis, as represented in the upper half of Figure , f. Nevertheless, the catalytic capability of the IEF might not be as effective as applied spatially and temporarily uniform EEFs since IEFs continuously change both in magnitude and direction as time evolves. Although the strengths of the EF found on microdroplets surfaces reported in the literature span several orders of magnitude, ranging from 10 5 to 10 9 V/m, , the fact that the larger fields used in the current work (i.e., 10 9 V/m) are not capable to dramatically modify the free energy landscape of the DA reaction suggests that orders of magnitude lower fields have negligible effects on its catalysis.