A molecular dynamics study of the equation of state and the structure of supercooled aqueous solutions of methanol

Corradini, Dario; Su, Zhiqiang; Stanley, H. Eugene; Gallo, Paola

doi:10.1063/1.4767060

Cited by 20 publications

(20 citation statements)

References 97 publications

(142 reference statements)

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“…The LLCP is still found to exist for low concentrations. 392 A FTS dynamical crossover was also measured in methanol solutions at low concentrations, 393 within this framework the FTS dynamical crossover should mark the crossing of the Widom line.…”

Section: Thermodynamics and Dynamics Of Aqueous Solutionsmentioning

confidence: 97%

Water: A Tale of Two Liquids

et al. 2016

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Water is the most abundant liquid on earth and also the substance with the largest number of anomalies in its properties. It is a prerequisite for life and as such a most important subject of current research in chemical physics and physical chemistry. In spite of its simplicity as a liquid, it has an enormously rich phase diagram where different types of ices, amorphous phases, and anomalies disclose a path that points to unique thermodynamics of its supercooled liquid state that still hides many unraveled secrets. In this review we describe the behavior of water in the regime from ambient conditions to the deeply supercooled region. The review describes simulations and experiments on this anomalous liquid. Several scenarios have been proposed to explain the anomalous properties that become strongly enhanced in the supercooled region. Among those, the second critical-point scenario has been investigated extensively, and at present most experimental evidence point to this scenario. Starting from very low temperatures, a coexistence line between a high-density amorphous phase and a low-density amorphous phase would continue in a coexistence line between a high-density and a low-density liquid phase terminating in a liquid–liquid critical point, LLCP. On approaching this LLCP from the one-phase region, a crossover in thermodynamics and dynamics can be found. This is discussed based on a picture of a temperature-dependent balance between a high-density liquid and a low-density liquid favored by, respectively, entropy and enthalpy, leading to a consistent picture of the thermodynamics of bulk water. Ice nucleation is also discussed, since this is what severely impedes experimental investigation of the vicinity of the proposed LLCP. Experimental investigation of stretched water, i.e., water at negative pressure, gives access to a different regime of the complex water diagram. Different ways to inhibit crystallization through confinement and aqueous solutions are discussed through results from experiments and simulations using the most sophisticated and advanced techniques. These findings represent tiles of a global picture that still needs to be completed. Some of the possible experimental lines of research that are essential to complete this picture are explored.

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Section: Thermodynamics and Dynamics Of Aqueous Solutionsmentioning

confidence: 97%

Water: A Tale of Two Liquids

et al. 2016

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“…There are several theoretical and computational studies of the phase behavior of supercooled aqueous solutions. [54][55][56][57][58][59][60][61][62] Paschek calculated the excess chemical potential of Ar in TIP5P-E water using the particle insertion method and found that the solubility of Ar in LDL is much higher than that in HDL. 62 Le and Molinero performed MD simulations of an aqueous solution of hydrophilic particles using a coarse-grained model.…”

Section: Introductionmentioning

confidence: 99%

“…Corradini et al calculated the isotherms of pressure using MD simulations for several solution systems. [54][55][56][57] They showed that the liquid-liquid critical point shifts to lower pressures and higher temperatures as the concentration of NaCl increases. 54,55 The liquid-liquid coexistence conditions of pure water is represented by a line in the pressuretemperature plane, whereas the coexistence conditions of an aqueous solution should be a twodimensional region in the plane for a value of composition.…”

Section: Introductionmentioning

confidence: 99%

Liquid-liquid separation of aqueous solutions: A molecular dynamics study

Yagasaki

Matsumoto

Tanaka

2019

The Journal of Chemical Physics

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In the liquid-liquid phase transition scenario, supercooled water separates into the high density liquid (HDL) and low density liquid (LDL) phases at temperatures lower than the second critical point. We investigate the effects of hydrophilic and hydrophobic solutes on the liquid-liquid phase transition using molecular dynamics simulations. It is found that a supercooled aqueous NaCl solution separates into solute-rich HDL and solute-poor LDL parts at low pressures. By contrast, a supercooled aqueous Ne solution separates into solute-rich LDL and solute-poor HDL parts at high pressures. Both the solutes increase the high temperature limit of the liquid-liquid separation. The degree of separation is quantified using the local density of solute particles to determine the liquid-liquid coexistence region in the pressure-temperature phase diagram. The effects of NaCl and Ne on the phase diagram of supercooled water are explained in terms of preferential solvation of ions in HDL and that of small hydrophobic particles in LDL, respectively.

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“…[57][58][59] Also solutions can represent a viable route to study the supercooled region of water. 21,[60][61][62][63][64][65] The existence of a FSC in concentrated solutions of methanol and of LiCl has been recently found [66][67][68] with ultrafast femtosecond optical Kerr effect (OKE) spectroscopy, nuclear magnetic resonance (NMR) diffusion measurements, Fourier-transform infrared (FTIR) measurements, and temperature-dependent rheology although different techniques, namely, broadband dielectric and light scattering spectroscopy in a broad frequency range experiments on water and LiCl(aq) do not find it. 69 The difference among the probes must, however, be considered while analyzing different kinds of relaxation times.…”

Section: Introductionmentioning

confidence: 99%

Fragile to strong crossover at the Widom line in supercooled aqueous solutions of NaCl

Gallo

Corradini

Rovere

2013

The Journal of Chemical Physics

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We study by molecular dynamics simulations the dynamical properties of an aqueous solution of NaCl at a concentration of 0.67 mol/kg upon supercooling. In a previous study of the same ionic solution, we have located the liquid-liquid critical point (LLCP) and determined the Widom line connected to the liquid-liquid transition. We present here the results obtained from the study of the self-intermediate scattering function in a large range of temperatures and densities approaching the LLCP. The structural relaxation is in agreement with the mode coupling theory (MCT) in the region of mild supercooling. In the deeper supercooled region the α-relaxation time as function of temperature deviates from the MCT power law prediction showing a crossover from a fragile to a strong behavior. This crossover is found upon crossing the Widom line. The same trend was found in bulk water upon supercooling and it appears almost unchanged by the interaction with ions apart from a shift in the thermodynamic plane toward lower pressures and higher temperatures. These results show that the phenomenology of supercooled water transfers from bulk to solution where the study of the supercooled region is experimentally less difficult.

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A molecular dynamics study of the equation of state and the structure of supercooled aqueous solutions of methanol

Cited by 20 publications

References 97 publications

Water: A Tale of Two Liquids

Water: A Tale of Two Liquids

Liquid-liquid separation of aqueous solutions: A molecular dynamics study

Fragile to strong crossover at the Widom line in supercooled aqueous solutions of NaCl

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