SPECTROSCOPIC AND DIELECTRIC-PROPERTIES OF LIQUID WATER - A MOLECULAR-DYNAMICS SIMULATION STUDY

The spectroscopic and dielectric properties of liquid water under an a mbient condition are studied via a molecular dynamics (MD) computer si mulation method. By employing the recent TAB/10D potential model [B. D . Bursulaya, J. Jeon, D. A. Zichi, and H. J. Kim, J. Chem. Phys. 108, 3286 (1997)], the evolving solvent electronic structure is incorporate d into the simulation. Thus both the induced dipole and polarizability variations of individual water molecules with the fluctuating nuclear configuration are accounted for. The MD results on far-IR absorption, depolarized Raman scattering (DRS) and optical Kerr effect (OKE) spec troscopy are in reasonable agreement with experiments. It is found tha t the nonlinear electronic response of water to its fluctuating enviro nment plays an important role in the DRS and OKE; it significantly enh ances the contribution of the water librational motions to the spectra , compared with that of hindered translations. This indicates that not only molecular dynamics but also accompanying electronic structure mo dulations are essential to quantitative understanding of various elect ronic spectroscopy. The effects of H/D isotope substitution are briefl y discussed. (C) 1998 American Institute of Physics.