Widom line and dynamical crossovers as routes to understand supercritical water

Gallo, Paola; Corradini, Dario; Rovere, Mauro

doi:10.1038/ncomms6806

Cited by 138 publications

(101 citation statements)

References 41 publications

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“…The states with and without PSD were called "liquidlike" and "gas-like" because they resemble the presence and absence of PSD in subcritical liquids and gases. The discussion of the effect of the Widom line on thermodynamic, dynamical and transport properties followed (see, e.g., [117,118]). …”

Section: Frenkel Linementioning

confidence: 99%

Collective modes and thermodynamics of the liquid state

2015

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Strongly interacting, dynamically disordered and with no small parameter, liquids took a theoretical status between gases and solids, with the historical tradition of hydrodynamic description as the starting point. We review different approaches to liquids as well as recent experimental and theoretical work, and propose that liquids do not need classifying in terms of their proximity to gases and solids or any categorizing for that matter. Instead, they are a unique system in their own class with a notably mixed dynamical state in contrast to pure dynamical states of solids and gases. We start with explaining how the first-principles approach to liquids is an intractable, exponentially complex problem of coupled non-linear oscillators with bifurcations. This is followed by a reduction of the problem based on liquid relaxation time τ representing non-perturbative treatment of strong interactions. On the basis of τ , solid-like high-frequency modes are predicted and we review related recent experiments. We demonstrate how the propagation of these modes can be derived by generalizing either hydrodynamic or elasticity equations. We comment on the historical trend to approach liquids using hydrodynamics and compare it to an alternative solid-like approach. We subsequently discuss how collective modes evolve with temperature and how this evolution affects liquid energy and heat capacity as well as other properties such as fast sound. Here, our emphasis is on understanding experimental data in real, rather than model, liquids. Highlighting the dominant role of solid-like high-frequency modes for liquid energy and heat capacity, we review a wide range of liquids: subcritical low-viscous liquids, supercritical state with two different dynamical and thermodynamic regimes separated by the Frenkel line, highly-viscous liquids in the glass transformation range and liquid-glass transition. We subsequently discuss the fairly recent area of liquid-liquid phase transitions, the area where the solid-like properties of liquids have become further apparent. We then discuss gas-like and solid-like approaches to quantum liquids and theoretical issues that are similar to the classical case. Finally, we summarize the emergent view of liquids as a unique system in a mixed dynamical state, and list several areas where interesting insights may appear and continue the extraordinary liquid story.

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Section: Frenkel Linementioning

confidence: 99%

Collective modes and thermodynamics of the liquid state

2015

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“…However, most models predict the existence of a LLCP at higher pressure, and thus, suggest a thermodynamic continuity of water at ambient pressure to very low temperature. Yet, a so-called Widom line emanates from the LLCP towards ambient pressure, 46,47 which connects the points of maxima with respect to temperature of a thermodynamic or dynamic property of water. Hence, in such a scenario, ambient properties of water may not diverge at T s but may approach a finite maximum near T s .…”

Section: Diffusion Activation Energymentioning

confidence: 99%

A physically constrained classical description of the homogeneous nucleation of ice in water

Koop

Murray

2016

The Journal of Chemical Physics

122

155

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Liquid water can persist in a supercooled state to below 238 K in the Earth's atmosphere, a temperature range where homogeneous nucleation becomes increasingly probable. However, the rate of homogeneous ice nucleation in supercooled water is poorly constrained, in part, because supercooled water eludes experimental scrutiny in the region of the homogeneous nucleation regime where it can exist only fleetingly. Here we present a new parameterization of the rate of homogeneous ice nucleation based on classical nucleation theory. In our approach, we constrain the key terms in classical theory, i.e., the diffusion activation energy and the ice-liquid interfacial energy, with physically consistent parameterizations of the pertinent quantities. The diffusion activation energy is related to the translational self-diffusion coefficient of water for which we assess a range of descriptions and conclude that the most physically consistent fit is provided by a power law. The other key term is the interfacial energy between the ice embryo and supercooled water whose temperature dependence we constrain using the Turnbull correlation, which relates the interfacial energy to the difference in enthalpy between the solid and liquid phases. The only adjustable parameter in our model is the absolute value of the interfacial energy at one reference temperature. That value is determined by fitting this classical model to a selection of laboratory homogeneous ice nucleation data sets between 233.6 K and 238.5 K. On extrapolation to temperatures below 233 K, into a range not accessible to standard techniques, we predict that the homogeneous nucleation rate peaks between about 227 and 231 K at a maximum nucleation rate many orders of magnitude lower than previous parameterizations suggest. This extrapolation to temperatures below 233 K is consistent with the most recent measurement of the ice nucleation rate in micrometer-sized droplets at temperatures of 227-232 K on very short time scales using an X-ray laser technique. In summary, we present a new physically constrained parameterization for homogeneous ice nucleation which is consistent with the latest literature nucleation data and our physical understanding of the properties of supercooled water. C 2016 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution (CC BY) license

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“…21. As it was shown in several recent publications the supercritical maxima of different substances rapidly vanish on departing from the critical point23456725.…”

mentioning

confidence: 83%

“…Widom line of TIP 4 P /2005 model is taken from ref. 21. Panel ( c ) enlarges the moderate pressure part of the diagram.…”

Section: Figurementioning

confidence: 98%

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Dynamical crossover line in supercritical water

Fomin

Ryzhov

Tsiok

et al. 2015

Sci Rep

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Dynamical crossover in water is studied by means of computer simulation. The crossover temperature is calculated from the behavior of velocity autocorrelation functions. The results are compared with experimental data. It is shown that the qualitative behavior of the dynamical crossover line is similar to the melting curve behavior. Importantly, the crossover line belongs to experimentally achievable (P, T) region which stimulates the experimental investigation in this field.

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Widom line and dynamical crossovers as routes to understand supercritical water

Cited by 138 publications

References 41 publications

Collective modes and thermodynamics of the liquid state

Collective modes and thermodynamics of the liquid state

A physically constrained classical description of the homogeneous nucleation of ice in water

Dynamical crossover line in supercritical water

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