Search for the superiority of supercritical water with ab initio molecular dynamics simulation

Water, from ambient state to supercritical state, plays diverse roles in various reactions. Especially, supercritical water appears more attractive for scientific and engineering applications, due to its unique physicochemical properties. Herein, by using ab initio molecular dynamic method, we studied the various structures and charge characteristics of the supercritical water with different densities mainly and com-pared it with multi-state water from 300 K to 800 K. The results demonstrate that supercritical water has a looser structure and weaker polarity than liquid water, and the decreasing density of supercritical water will enhance such a tendency, which promote the solubility of organics in it and the reactivity of water. What's more interesting is the mutation of hydrogen bonds and spectrum while the temperature rises to cross the supercritical point. For supercritical water, the molecules are mostly monomers, and the vibra-tional mode is close to but still lower than that of the gas phase. The calculated parameters of supercrit-ical water are close to the actual applications, which is demonstrated by the complete gasification of the model compounds, diphenylethane, in experiments. Moreover, this work provides a reference for research and development of the wide application of supercritical water in practice.(c) 2022 Elsevier B.V. All rights reserved.

Automated summary

In this study, the various structures and charge characteristics of supercritical water with different densities were investigated using first-principles molecular dynamic method. It was found that supercritical water has a looser structure and weaker polarity than liquid water, promoting the solubility of organics and reactivity of water. The hydrogen bonds and spectrum of supercritical water change as the temperature rises, especially upon crossing the supercritical point.