We then attempted to reproduce the same increase in vibronic broadening seen for the QM solvent optimized structures by increasing the van der Waals radii by 0.30 Å for all atoms within the QUBEKit force field. This increase in van der Waals radii was chosen so that optimizing the ground state chromophore geometry within an MM solvent environment produced peripheral H-bond distances similar to those obtained when optimizing within a QM solvent shell (see SI, section S10). Additionally, 0.30 Å is also close to the difference in potential minima between the QM-QM/MM and QUBEKit interaction energies shown in Figure . The resulting spectra generated from optimized geometries with the solvent only treated at the MM level remarkably mimic the spectral width of the chromophore optimized with the QM H-bonded solvent. These findings indicate that peripheral H-bonds play an important role in determining the vibronic broadening of CV + in methanol, with an MM treatment of these solvent molecules potentially restricting the motion of the QM chromophore and decreasing vibronic coupling. A QM treatment of the solvent during either the geometry optimization or potentially also during the MD may be essential to producing the correct chromophore-solvent distances and allowing for the full vibronic coupling of the chromophore.