While adjusting the damping factor can yield a more detailed vibronic spectrum, the convergence of the correlation functions becomes more challenging. In contrast, for the CD spectrum, exciton coupling results in positive and negative signals that, although partially canceling each other out, still preserve the primary vibrational structure, thereby revealing details that are not present in the absorption spectrum. Compared to the non-vibronic spectrum, in the high-energy region of the CD spectrum (above 20000 cm -1 ), the introduction of vibronic coupling significantly enhances the positive signals and causes a blue shift, while in the low-energy region, the signals are enhanced and undergo a red shift. The overall effect is that the vibronic spectrum appears broader compared to the spectrum yielded by TD-DFT approach.