All the simulations are performed under room temperature T = 300 K. For the monomer, the linear spectra in Fig. were computed using Eq. 2, which is a smoothed Fourier transform of the response function R (1) (t) in Eq. 1. We obtain R (1) (t) (Eq. 1) by performing the L-PLDM simulation using 10 5 trajectories, with the dynamics governed in Eq. 29. The initial nuclear configurations are sampled from Eq. 10, and the initial mapping variables are chosen based on the focused initial condition (see Eq. 48). The total simulation time is 300 fs for the R (1) (t), which guarantees a converged R (1) (ω).