The detailed description of wavelet analysis is shown in the SI. In Fig. (c), the high-frequency mode of 996 cm -1 (marked as black dashed line in Fig. )) shows a long-lived oscillation and it lasts longer than 500 fs. The relative lifetime of magnitude is shown as 803 fs in Fig. , which indicates that the vibrational coherence of intramolecular mode (Holstein mode) is fully occupied and mediate the process of the SF. On the basis of our calculations, we manifest that vibronic coupling of two vibrational modes (intramolecular and intermolecular modes) degenerate the potential energy surfaces and drive the ultrafast deactivation in the model of pentacene dimer (the potential energy surfaces and the degenerate point in the SI). Our previous studies also concluded that the intramolecular mode persist for a long lifetime and mediate the population transfer from electronic singlet state to the triplet-pair state , which agrees to our observation in the calculations of pentacene model. Also, the low-frequency modes of 109 and 259 cm -1 is close to the frequency of intermoelcular motion, 177 cm -1 . In our previous work, we observe the low-frequency coherence is split into two modes when the wave packet approaching to the degenerate point between two potential energy surfaces . In Fig. , the calculated results show the relatively lifetimes with weaker magnitude. It implies that the original mode of 177 cm -1 can not pass through the conical intersection between singlet and triplet-pair states and the motion of wave packet splits into two vibrational modes at 109 and 259 cm -1 , respectively. Interestingly, we also observe a new mode with coherent oscillation of frequency 434 cm -1 , which is plotted as red solid line in Fig.