Numerical Study of Vibrational Energy Relaxation of OH Bending in Liquid H2O

The relaxation of O-H bending of water molecule H2O in the liquid phase was studied with the molecular dynamics simulation approach. Both rigid and flexible solvents were used to identify the different channels for the vibrational energy relaxation. It was observed that the relaxation time for the O-H bend overtone is 174 fs in the rigid solvent while it is 115 fs in the flexible solvent. The main pathway of the O-H bend overtone is transition to the bend fundamental. The relaxation time of the O-H bend fundamental was calculated as 204 fs which is comparable to the experimental value 170 fs.