In the high energy window, the mean value of the E10 energy gap in the stationary regime was 3.31 eV (Table ), which is 0.24 eV redshifted from the vertical excitation at the S1 minimum (Table ). In the low-energy window, this redshift is 0.16 eV. The mean E20 energy gap is redshifted from the vertical value at the S2 minimum by 0.22 eV in the high-and 0.19 eV in the low-energy windows. The mean S1→S0 oscillator strength grows 27 times in the high-energy window (17 times in the low one) compared to its value at the S1 minimum. This growth is due to the vibronic coupling with the S2 state when pyrene loses its planarity during dynamics. The mean oscillator strength of S2 drops from 0.544 at the S2 minimum to about 0.3 in both excitation windows. Nevertheless, this S2-emission dominance is not experimentally observed. The disagreement is due to vibronic couplings induced by the symmetry breaking during the vibrational motion, causing the oscillator strength of S1 to be much stronger. VCA cannot predict vibronic couplings, but if we assume that the mean oscillator strength of S1 is 15 times bigger than at the S1 minimum, the emission spectrum changes substantially, as shown in Figure (b). (We have seen in Section III.2 that the mean value of the S1 oscillator strength indeed increases 27 times compared to the vertical value. However, we want to keep the discussion about the VCA spectrum entirely independent of the dynamics. For this reason, we will proceed with this 15 times hypothetical value.) Considering vibronic coupling, S1 dominates the emission, and the S2 signal becomes a shoulder, as experimentally observed. Note yet that the S2 emission does not change significantly between both simulations for a 5.7-eV excitation. Its maximum intensity remains at about 0.610 -8 . However, the S1 intensity increases by a factor of fifteen.