The spectral density of pure water with the SPC/Fw forcefield, shown as the dot dashed blue curve in Fig. , reveals the origin of the peak at 1500 cm -1 seen in the gap correlation function of e - (aq) at the Flexi-BLE QM/MM level (solid black curve in Fig. ): this peak arises from coupling between the excess electron and the MM SPC/Fw water molecules' bend. SPC/Fw was parameterized to reproduce structural, thermodynamic, and kinetic, rather than vibrational, properties of liquid water, and the bend frequency is evidently underesti-mated in this model. Although our use of the SPC/Fw model results in a spurious secondary water bend peak in e - (aq) 's energy gap fluctuations, we view this as serendipitous, as it allows us to easily separate the coupling of the excess electron to QM and MM water bend vibrations, which we see to be dominated by the former.