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Translational and Rotational Diffusion in Liquid Water at Very High Pressure: A Simulation Study

Abstract : Translational and rotational diffusion coefficients of liquid water have been computed from molecular dynamics simulation with a recent polarizable potential at 298, 400, and 550 K at very high pressure. At 298 K, the model reproduces the initial increase and the occurrence of a maximum for the translational and rotational diffusion coefficients when the pressure increases. At 400 and 550 K, translational and rotational diffusion coefficients are found to monotonically decrease when pressure increases in the gigapascal range, with the translational coefficient decreasing faster than the rotational one. At 400 K, such an evolution of the rotational diffusion coefficient contrasts with quasielastic neutron scattering results predicting a near independence of the rotational diffusion with a pressure increase above ≃0.5 GPa. An interpretation is proposed to explain this discrepancy. The pressure dependence of the translation–rotation coupling is analyzed. The anisotropy of rotational diffusion is investigated by computing the rotational diffusion tensor in a molecular system of axes and the reorientational correlation times of rank 1 and rank 2 of the inertia axes and of the OH bond vector. Deviation of the simulation data with respect to the predictions of the isotropic Debye model of rotational diffusion are quantified and can be used to estimate experimental rotational diffusion coefficients from experimental reorientational correlation times.
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Contributor : Jean-François Wax Connect in order to contact the contributor
Submitted on : Tuesday, August 25, 2020 - 2:38:55 PM
Last modification on : Sunday, June 26, 2022 - 2:52:47 AM



Pascale Friant-Michel, Jean-François Wax, Nadège Meyer, Hong Xu, Claude Millot. Translational and Rotational Diffusion in Liquid Water at Very High Pressure: A Simulation Study. Journal of Physical Chemistry B, American Chemical Society, 2019, 123 (47), pp.10025-10035. ⟨10.1021/acs.jpcb.9b06884⟩. ⟨hal-02921734⟩



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