Optical Kerr effect spectroscopy of liquid water: Role of fluctuating electronic polarizability

The third-order nonlinear nuclear Kerr response of liquid water is studied via molecular dynamics computer simulations. By employing the TAB/10 potential model recently developed in our group, the instantaneous adjustment of molecular polarizability to the fluctuating local electric field is properly accounted for. It is found that the fluctuating nonlinear aspect of electronic polarizability has dramatic effects on Kerr response. It strongly enhances the librational character of, and introduces short-time oscillatory structures into, the water response function, compared to a linear description with fixed polarizability. Thus despite its small anisotropy, TAB/10 water yields good overall agreement with recent experimental findings of optical Kerr effect spectroscopy.