Although the broader emission spectra likely contain contributions from overly strong chromophore-solvent interactions in the excited state, which may contribute to the overestimation of the Stokes shift values, see Table , they likely also originate from the CAM-B3LYP density functional within the TDA predicting an overly flat excited state potential in explicit QM solvent. This overly flat potential would manifest in both a wider distribution of chromophore configurations sampled during the excited state AIMD and a wider vibronic spectrum, as we see in our average FC lineshapes. This explanation is supported by the much more narrow spectrum generated by a vertical gradient compared to adiabatic Hessian Franck-Condon lineshape (see Figure ) as well as going beyond the TDA to employing the full TDDFT matrix, which leads to a slight broadening of the absorption spectrum and narrowing of the emission spectrum (see Figure ). The difference in absorption and emission spectral width also shows some mild dependence on the choice of functional, with LC-ωPBE yielding a more narrow fluorescence spectrum (see Figure ). In sum, the E-FC methods capture both specific environmental and vibronic effects but are susceptible to errors in the description of the electronic structure, which for NBD in DMSO at the TDA/CAM-B3LYP level of theory appears to yield an overly flat description of the excited state potential.