Vibrational energy relaxation of the OH stretch in liquid methanol

The state-to-state rate of vibrational energy relaxation of the OH-stretch fundamental is investigated via perturbative methods. The system is separated into an 11 degree of freedom methanol molecule and the surrounding bath. Notably, the large amplitude torsional motion is considered a bath degree of freedom, and the 11 small amplitude normal modes are expanded in a Fourier series of the torsional angle. The methanol-bath coupling is computed through the use of a molecular dynamics simulation, and the results are computed using Landau-Teller and time dependent perturbation theory. Results are compared to the ultrafast pump-probe experiments of L. K. Iwaki and D. D. Dlott.