The low-frequency region of the spectral density, shown as an inset in Figure , is dominated by the slower solvent degrees of freedom and is responsible for the inhomogeneous broadening in the optical spectrum. Here we see that the QUBEKit trajectory, with no ax- ial H-bonding, produces significantly less intensity in the low-frequency region, suggesting weaker coupling of CV + to the solvent environment. Notably, the revQUBEKit trajectory produces an increase in intensity, with lowfrequency results that align fairly well with the QM/MM trajectory. We hypothesize that the increased intensity for both the QM/MM and the revQUBEKit trajectories is due to the axial H-bond and the strong electric field generated that is aligned with the π-system of the chromophore.