The Widom line and dynamical crossover in supercritical water: Popular water models versus experiments

Abstract

In a previous study [Gallo et al., Nat. Commun. 5, 5806 (2014)], we have shown an important connection between thermodynamic and dynamical properties of water in the supercritical region. In particular, by analyzing the experimental viscosity and the diffusion coefficient obtained in simulations performed using the TIP4P/2005 model, we have found that the line of response function maxima in the one phase region, the Widom line, is connected to a crossover from a liquid-like to a gas-like behavior of the transport coefficients. This is in agreement with recent experiments concerning the dynamics of supercritical simple fluids. We here show how different popular water models (TIP4P/2005, TIP4P, SPC/E, TIP5P, and TIP3P) perform in reproducing thermodynamic and dynamic experimental properties in the supercritical region. In particular, the comparison with experiments shows that all the analyzed models are able to qualitatively predict the dynamical crossover from a liquid-like to a gas-like behavior upon crossing the Widom line. Some of the models perform better in reproducing the pressure-temperature slope of the Widom line of supercritical water once a rigid shift of the phase diagram is applied to bring the critical points to coincide with the experimental ones.

Mode coupling theory and fragile to strong transition in supercooled TIP4P/2005 water

“…This result is a further confirmation that in water the dynamics is intimately related to thermodynamics in all its very complex phase diagram, as made evident also from the recent results on its supercritical phase 40,41 where a dynamic crossover from a gas-like to a liquid-like phase has been found upon crossing the Widom Line of the liquid-gas critical point.…”

“…17,18,34 We note that experiments and computer simulations on several popular water all atoms potentials in supercritical water show that the maxima of the response functions collapse on the Widom line well above the liquid gas critical point. 40,41 In TIP4P/2005, in particular, they collapse for a range of circa 30 K in temperature above the liquid gas critical point. 40 By considering the LLCP to be the source of its thermodynamic peculiarities a consistent description of the phenomenology of supercooled water is obtained.…”

EDTA aggregates induce SYPRO orange-based fluorescence in thermal shift assay

“…In line with these data, the EDTA 4— Na + aggregates display a bilayer-like configuration (S9D Fig) that appears more compact than at 300 K (Fig 3B). Although these results may be influenced in that the TIP3P water model used in the MD simulations displays difficulties reproducing experimental values for water at higher temperatures [45, 46], our results indicate that increasing temperature fosters EDTA 4- aggregation, but does not influence the solution behavior of EDTA 3- .…”

Communication: Diffusion constant in supercooled water as the Widom line is crossed in no man’s land

“…Within the LLCP scenario, the Widom line extends from the critical point at high pressures, all the way to (and past) 1 bar. Notably, the Widom line is closely approximated by the line of maximum compressibility, [14][15][16][17] and hence, within this scenario, at 1 bar the compressibility grows because the Widom line is being approached.…”