Coarse-grained approach to nonequilibrium molecular dynamics: Application to relaxation process of vibrationally excited hydrogen fluoride in aqueous solution

Using a coarse-grained approach, the energy relaxation dynamics in a vibrationally excited HF molecule in aqueous solution is investigated. The space-time-resolved power spectral distribution of water can be represented with 0.1 ps × 0.5 Å × 0.5 Å resolution. It was found that the relaxation consists of two processes: one that spectral intensities increase over the broad off-resonant frequency range, and the other that such hot water molecules return to equilibrium by propagating their excess energy to the surrounding. The approach is significant in the sense to visualize the relaxation pathway from not only time-resolved but also space-resolved perspective.