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Updated: Dec 15, 2025

Synthesis and Microdiffraction at Extreme Pressures and Temperatures
Published on: October 7, 2013
Thermodynamics, dynamics, and structure of supercritical water at extreme conditions
Tae Jun Yoon1, Lara A Patel1, Taeho Ju1
1Los Alamos National Laboratory, P.O. Box 1663, Los Alamos, NM 87545, USA. tyoon@lanl.gov.
Abstract:
Molecular dynamics (MD) simulations to understand the thermodynamic, dynamic, and structural changes in supercritical water across the Frenkel line and the melting line have been performed. The two-phase thermodynamic model [J. Phys. Chem. B, 2010, 114(24), 8191-8198] and the velocity autocorrelation functions are used to locate the Frenkel line and to calculate the thermodynamic and dynamic properties. The Frenkel lines obtained from the two-phase thermodynamic model and the velocity autocorrelation criterion do not agree with each other. Structural characteristics and the translational diffusion dynamics of water suggest that this inconsistency could arise from the two oscillatory modes in water, which are associated with the bending of hydrogen bonds and intermolecular collisions inside the first coordination shell. The overall results lead us to conclude that the universality of the Frenkel line as a dynamic crossover line from rigid to nonrigid fluids is preserved in water.
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