Supercritical Water is not Hydrogen Bonded

Abstract

Thinking about water is inextricably linked to hydrogen bonds,w hicha re highly directional in character and determine the unique structure of water,i np articular its tetrahedral H-bond network. Here,w ea ssess if this common connotation also holds for supercritical water.W ee mploy extensive ab initio molecular dynamics simulations to systematically monitor the evolution of the H-bond network mode of water from room temperature,w here it is the hallmark of its fluctuating three-dimensional network structure,t os upercritical conditions.O ur simulations reveal that the oscillation period required for H-bond vibrations to occur exceeds the lifetime of H-bonds in supercritical water by far.I nstead, the corresponding low-frequency intermolecular vibrations of water pairs as seen in supercritical water are found to be well represented by isotropic van-der-Waals interactions only. Based on these findings,w ec onclude that water in its supercritical phase is not aH-bonded fluid.

Machine learning potentials for complex aqueous systems made simple

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Ion association in hydrothermal aqueous NaCl solutions: implications for the microscopic structure of supercritical water

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Hydrogen Bonding and the Structural Properties of Glycerol–Water Mixtures with a Microwave Field: a Molecular Dynamics Study

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“…This is due to the fact that we applied microwave field with an extremely high amplitude (i.e., 3 × 10 8 V/m) and stored trajectories every 5 fs in order to be able to obtain accurate profiles in a reasonable MD simulation time. All our production simulations are at 534 K and 14 bar; the temperature and pressure are lower than the corresponding supercritical condition values (647 K and 221 bar) . The generated trajectories were stored every 50 fs.…”