Molecular Dynamics Simulations for Optical Kerr Effect of Liquid and Supercooled Water*

The optical Kerr effect (OKE) spectroscopy measured with heterodyne detection (HD) is a useful tool to provide information regarding intermolecular vibrations and structural relaxations in liquid water. Recently, the measurements of the OKE spectroscopy have been extended to supercooled water [1]. Though the measured results can be well described by using a phenomenological model, the time-resolved OKE spectroscopy of liquid and supercooled water still need a comprehensive understanding. In this paper, we investigated the OKE nuclear response functions of this peculiar liquid and their reduced spectral densities by performing molecular dynamics simulations with the TIP4P/2005 water model [2]. The collective polarizability of water was computed via a dipolar induction scheme, which involves the intrinsic polarizability and the first-order hyperpolarizability tensor of water molecule. Our simulation results were consistent with the HD-OKE experimental observations. The effects due to the first-order hyperpolarizability of water molecule were examined.

[1] A. Taschin, P. Bartolini, R. Eramo, R. Righini, and R.Torre, Nature Commun. 4, 2401 (2013).
[2] P. H. Tang and T. M. Wu, J. Mol. Liq. 269, 38 (2018).