Two-state thermodynamics of the ST2 model for supercooled water

Holten, Vincent; Palmer, Jeremy C.; Poole, Peter H.; Debenedetti, Pablo G.; Анисимов, М. А.

doi:10.1063/1.4867287

Cited by 113 publications

(145 citation statements)

References 77 publications

(138 reference statements)

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“…The application of this picture to the OKE data analysis suggests that liquid water consists of mixture of four different clusters, having comparable and weakly temperature dependent concentrations. The most recent experimental investigations 1,54 , simulation studies 55,56 and theoretical models [57][58][59] do not support this scenario: the emerging picture is that water presents a bimodal local structuring (i.e. formation of two main molecular clusters); water molecules form local structures either tetrahedrally coordinated, named low-density forms, or close-packed, named high-density form.…”

Section: Kdrj Fitting Details and Resultsmentioning

confidence: 99%

Optical Kerr effect of liquid and supercooled water: The experimental and data analysis perspective

Taschin¹,

Bartolini²,

Eramo³

et al. 2014

The Journal of Chemical Physics

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The time-resolved optical Kerr effect spectroscopy (OKE) is a powerful experimental tool enabling accurate investigations of the dynamic phenomena in molecular liquids. We introduced innovative experimental and fitting procedures, that permit a safe deconvolution of sample response function from the instrumental function. This is a critical issue in order to measure the dynamics of sample presenting weak signal, e.g. liquid water. We report OKE data on water measuring intermolecular vibrations and the structural relaxation processes in an extended temperature range, inclusive of the supercooled states. The unpreceded data quality makes possible a solid comparison with few theoretical models; the multi-mode Brownian oscillator model, the Kubo's discrete random jump model and the schematic mode-coupling model. All these models produce reasonable good fits of the OKE data of stable liquid water, i.e. over the freezing point. The features of water dynamics in the OKE data becomes unambiguous only at lower temperatures, i.e. for water in the metastable supercooled phase. Hence this data enable a valid comparison between the model fits. We found that the schematic mode-coupling model provides the more rigorous and complete model for water dynamics, even if is intrinsic hydrodynamic approach hide the molecular informations.

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Section: Kdrj Fitting Details and Resultsmentioning

confidence: 99%

Optical Kerr effect of liquid and supercooled water: The experimental and data analysis perspective

Taschin¹,

Bartolini²,

Eramo³

et al. 2014

The Journal of Chemical Physics

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show abstract

“…Once this is confirmed, precision fitting of the anomalies can provide additional insights 24,36 . Successful two-state descriptions of related water models, like the ST2 potential 38 and the mW potential 41 also suggest the viability of this approach. For this reason, we have also provided an approximate scheme to extract the model's parameters from experimentally accessible measurements.…”

Section: Discussionmentioning

confidence: 99%

“…From a phenomenological standpoint, two-state models have been extremely successful in describing the anomalies of water using a restricted number of fitting parameters [23][24][25][26]36 , and recent simulations by Cuthbertson and Poole 37 have opened the way for a quantitative assessment of these models from microscopic information, but only for state points around the Widom line, that is, at temperatures not accessible to experiments and far from the anomalies. For the same water model, the validity of a twostate model with excess free enthalpy (see equation (1)) has been recently assessed 38 . The essential difficulty in defining locally favoured states is finding a structural order parameter that directly correlates with water's anomalies.…”

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confidence: 99%

Understanding water’s anomalies with locally favoured structures

2014

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Water is a complex liquid that displays a surprising array of unusual properties, the most famous being the density maximum at about 4°C. The origin of these anomalies is still a matter of debate, and so far a quantitative description of water's phase behaviour starting from the molecular arrangements is still missing. Here we report a study of the microscopic structural features of water as obtained from computer simulations. We identify locally favoured structures having a high degree of translational order in the second shell, and a two-state model is used to describe the behaviour of liquid water over a wide region of the phase diagram. Furthermore, we show that locally favoured structures not only have translational order in the second shell but also contain five-membered rings of hydrogenbonded molecules. This suggests their mixed character: the former helps crystallization, whereas the latter causes frustration against crystallization.

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“…The existence of two structures does not necessarily mean that phase separation will occur [17,[39][40][41]. However, if the mixture of two structures is sufficiently non-ideal, a positive excess Gibbs energy of mixing could cause phase separation [34,42].…”

Section: Introductionmentioning

confidence: 99%

Behavior of supercooled aqueous solutions stemming from hidden liquid–liquid transition in water

Biddle

Holten

Анисимов

2014

The Journal of Chemical Physics

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A popular hypothesis that explains the anomalies of supercooled water is the existence of a metastable liquid-liquid transition hidden below the line of homogeneous nucleation. If this transition exists and if it is terminated by a critical point, the addition of a solute should generate a line of liquid-liquid critical points emanating from the critical point of pure metastable water. We have analyzed thermodynamic consequences of this scenario. In particular, we consider the behavior of two systems, H2O-NaCl and H2O-glycerol. We find the behavior of the heat capacity in supercooled aqueous solutions of NaCl, as reported by Archer and Carter, to be consistent with the presence of the metastable liquid-liquid transition. We elucidate the non-conserved nature of the order parameter (extent of "reaction" between two alternative structures of water) and the consequences of its coupling with conserved properties (density and concentration). We also show how the shape of the critical line in a solution controls the difference in concentration of the coexisting liquid phases.

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Two-state thermodynamics of the ST2 model for supercooled water

Cited by 113 publications

References 77 publications

Optical Kerr effect of liquid and supercooled water: The experimental and data analysis perspective

Optical Kerr effect of liquid and supercooled water: The experimental and data analysis perspective

Understanding water’s anomalies with locally favoured structures

Behavior of supercooled aqueous solutions stemming from hidden liquid–liquid transition in water

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