Simulation Study on the Structure and Dynamics of Water in Sodium Tetrafluoroborate/Water

The microstructure, IR spectrum, as well as rotation dynamics of water molecule in sodium tetrafluoroborate (NaBF₄)/water mixture at room temperatures were studied with molec- ular dynamics simulation. Different concentrations of water (6.25%, 25.0%, 50.0%, 75.0%, 90.0%, and 99.6%) in NaBF₄/water mixture were simulated to understand the structure and dynamics. It was shown that water molecules tend to be isolated from each other in mixtures with more ions than water molecules in both liquids. With increase of the molar fraction of water in the mixture, the rotation bands and the bending bands of water display red shift whereas the O-H stretch bands show blue shift, and the decay of the reorientation correlation function becomes slower. This suggests that the molecules are hindered and their motions are difficult and slow, due to the hydrogen-bond interactions and the inharmonic interactions between the inter- or intra-molecular modes.