On this basis, 16 H2O molecules appear as a plausible choice that should correspond to an essentially complete first hydration shell of the adsorbed 5-FU molecule. The simulations of co-adsorbed 5-FU and water considered only H-FAU_1H, H-FAU_2H_1_3, and H-FAU_2H_1_4. Since these simulations were aimed primarily at qualitative insights, only a single trajectory was computed for each system, but for an extended time period of 25 ps.