To understand the role of solvent and intramolecular vibrations on the decoherence, Fig. shows the contributions due to solvent (blue line), vibrations (dashed line), and solvent plus specific vibrational modes (yellow and orange lines). As shown, the early-time decoherence dynamics is dominated by vibrational contributions while the overall coherence decay is dictated by the solvent. Out of all vibrational modes in the molecule, we find that the mode at 1663 cm -1 , plays the most important role. In fact, taking into account the solvent and just three peaks due to intramolecular vibrations (at 1663 cm -1 , 1376 cm -1 and 1243 cm -1 ) accounts for most of the decoherence dynamics (yellow line). Overall, these results demonstrate the close interplay between solvent and intramolecular vibrations in the decoherence dynamics.