Since its discovery, a general consensus has emerged that the hydrated electron occupies a quasi-spherical cavity in liquid water. To simulate this desired cavity, we first equilibrated a 24 × 24 × 24 Å3 periodic box containing 81 water molecules, a PFOA or PFOS molecule, and a chloride ion in an NVT (constant number N , volume V , and temperature T ) canonical ensemble for over 10 ps with a 1 fs time step. A large simulation box was used to prevent chemical species from interacting artificially with its periodic image. The approximate dimensions of the PFOA and PFOS molecules are provided in the Supporting Information. After the equilibration step, we created five independent trajectories whose initial conditions were obtained from the last 5 ps of the PFOA/PFOS simulation (i.e., 5 independent trajectories were generated for each PFOA and PFOS configuration). Finally, for each of these 5 PFOA/PFOS trajectories, the chloride ion was removed, and the system was then initialized with an extra negative charge to generate the desired hydrated electron.