Waterlike hierarchy of anomalies in a continuous spherical shouldered potential

Oliveira, Alan Barros de; Franzese, Giancarlo; Netz, Paulo Augusto; Barbosa, Márcia C.

doi:10.1063/1.2830706

Cited by 135 publications

(156 citation statements)

References 67 publications

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“…This scheme is based on the assumption that water-water interaction is characterized by an isotropic component, a directional component, and a cooperative component and that H-bond formation leads to an open local structure. Alternative mechanisms, based only on isotropic interactions (45)(46)(47)(48)(49) or only on directional interactions (50) have been considered and their relevance for the water case is an open question. Finally, estimates for the three components of the H-bond interaction, based on experimental data lead to the conclusion that the LLCP scenario with a positive critical pressure holds for water.…”

Section: Discussionmentioning

confidence: 99%

Effect of hydrogen bond cooperativity on the behavior of water

Stokely

Mazza

Stanley

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

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Four scenarios have been proposed for the low-temperature phase behavior of liquid water, each predicting different thermodynamics. The physical mechanism that leads to each is debated. Moreover, it is still unclear which of the scenarios best describes water, because there is no definitive experimental test. Here we address both open issues within the framework of a microscopic cell model by performing a study combining mean-field calculations and Monte Carlo simulations. We show that a common physical mechanism underlies each of the four scenarios, and that two key physical quantities determine which of the four scenarios describes water: (i) the strength of the directional component of the hydrogen bond and (ii) the strength of the cooperative component of the hydrogen bond. The four scenarios may be mapped in the space of these two quantities. We argue that our conclusions are model independent. Using estimates from experimental data for H-bond properties the model predicts that the low-temperature phase diagram of water exhibits a liquid-liquid critical point at positive pressure.anomalous liquids | liquid-liquid transition | liquid water | mean field | Monte Carlo simulations W ater's phase diagram is rich and complex: more than sixteen crystalline phases (1), and two or more glasses (2-4) have been reported. The liquid state also displays interesting behavior, such as the density maximum for 1 atm at 4°C. The volume fluctuations hðδV Þ 2 i, entropy fluctuations hðδSÞ 2 i, and cross fluctuations between volume and entropy hδV δSi, proportional to the magnitude of isothermal compressibility K T , isobaric specific heat C P , and isobaric thermal expansivity α P , respectively, show anomalous increases in magnitude upon cooling (5). Further, these quantities display an apparent divergence for 1 atm at −45°C (2), hinting at interesting phase behavior in the supercooled region.Microscopically, liquid water's anomalous behavior is understood as resulting from the tendency of neighboring molecules to form hydrogen (H) bonds upon cooling with a decrease of local potential energy, decrease of local entropy, and increase of local volume due to the formation of local open structures of bonded molecules. Different models include these H-bond features, but depending on the assumptions and approximations of each model, different conclusions are obtained for the low-T phase behavior. The relevant region of the bulk-liquid state cannot be probed experimentally, and none of the theories tested because crystallization of bulk water is unavoidable below the homogeneous nucleation temperature T H (−38°C at 1 atm). Four Scenarios for Supercooled WaterDue to the difficulty of obtaining experimental evidence, theoretical and numerical analyses are useful. Four separate scenarios for the pressure-temperature (P-T) phase diagram have been proposed: (I) The stability limit (SL) scenario (6) hypothesizes that the superheated liquid-gas spinodal at negative pressure reenters the positive P region below T H ðPÞ. In this view, the liq...

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Section: Discussionmentioning

confidence: 99%

Effect of hydrogen bond cooperativity on the behavior of water

Stokely

Mazza

Stanley

et al. 2010

Proc. Natl. Acad. Sci. U.S.A.

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256

250

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“…These findings were also supported by simulations both in atomistic 13,14 and in effective models. [15][16][17][18] The addition of a solute might change the position or even the existence of the anomalies in the pressure-temperature phase diagram of these model systems.…”

Section: Introductionmentioning

confidence: 99%

Structure and anomalous solubility for hard spheres in an associating lattice gas model

Szortyka

Girardi

Henriques

et al. 2012

The Journal of Chemical Physics

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In this paper we investigate the solubility of a hard-sphere gas in a solvent modeled as an associating lattice gas. The solution phase diagram for solute at 5% is compared with the phase diagram of the original solute free model. Model properties are investigated both through Monte Carlo simulations and a cluster approximation. The model solubility is computed via simulations and is shown to exhibit a minimum as a function of temperature. The line of minimum solubility (TmS) coincides with the line of maximum density (TMD) for different solvent chemical potentials, in accordance with the literature on continuous realistic models and on the "cavity" picture.

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“…It is accepted that the presence of two accessible length scales in the potential allow for the system to have two liquid phases and a density anomaly. The accessibility is the ingredient that explains why a density anomaly derived in 1D does not necessarily hold at higher dimensions and why a density anomaly derived for a smooth potential might be lost if the slope linking the two length scales becomes infinite [20][21][22] .In this letter we show, by means of an exactly solvable 1D model and numerical simulations of a similar 3D potential, that a three length scales potential might exhibit three critical points and two density anomalous regions if the different length scales would be accessible. To the best of our knowledge this is the first time that core softened potentials are shown to have three critical points and two temperature of maximum density lines.…”

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Multiple liquid-liquid critical points and density anomaly in core-softened potentials

2013

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The relation between liquid-liquid phase transitions and waterlike density anomalies in coresoftened potentials of fluids was investigated in an exactly solvable one dimensional lattice model and a in a three dimensional fluid with fermi-like potential, the latter by molecular dynamics. Both systems were shown to present three liquid phases, two liquid-liquid phase transitions closely connected to two distinct regions of anomalous density increase. We propose that an oscillatory behavior observed on the thermal expansion coefficient as a function of pressure can be used as a signature of the connection between liquid-liquid phase and density.PACS numbers: 61.20. Gy, The phase behavior of single component systems as particles interacting via the o-called core-softened (CS) potentials has received attention since the pioneering work of Stell and Hemmer proposing the possibility of a second critical point in addition to the usual liquidgas critical point 1 . These potentials exhibit a repulsive core with a softening region with a shoulder or a ramp 1-3 which are analytically and computationally tractable while being capable of retaining the qualitative features of the real fluid systems. Furthermore, Debenedetti and collaborators 4 using thermodynamic arguments showed that the isobaric thermal expansion coefficient (α) of these potentials might have an anomalous negative value and consequently a region where density increases with temperature. Since for high temperatures density decreases with temperature these potentials can exhibit a temperature of maximum density (TMD) connecting the two regions.The thermodynamic anomalies predicted by these models occur in liquids such as Te 5 , Ga, Bi 6 , S 7,8 , liquid water 9 , and Ge 15 Te 85 10 , and were found in simulations for silica 11,12 , silicon 13 , and BeF 2 11 . In addition experiments in phosphorous indicate the presence of a liquidliquid phase transition 14 and similar transitions were observed by simulations in models of silica 15 , silicon 13 and liquid water 16 .In the particular case of water the hypothesis of the existence of two liquid phases has been indirectly supported by experimental results in confined systems 17 . In spite of the limit of 235 K below which water cannot be found in the liquid phase without crystallization, two amorphous phases, a low density amorphous phase and a high density amorphous phase, were observed at much lower temperatures and their relation to a metastable liquidliquid phase transition was argued 18 . More recently a third amorphous phase, the very high density amorphous phase, has been observed 19 what suggests the possibility of the existence of the very high density liquid phase.Therefore the issue of a liquid-liquid phase transition and its connection with the existence of a region in the pressure-temperature phase diagram where the density decreases with the decrease of temperature is itself an interesting topic. It is accepted that the presence of two accessible length scales in the potential allow for the system to ...

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Waterlike hierarchy of anomalies in a continuous spherical shouldered potential

Cited by 135 publications

References 67 publications

Effect of hydrogen bond cooperativity on the behavior of water

Effect of hydrogen bond cooperativity on the behavior of water

Structure and anomalous solubility for hard spheres in an associating lattice gas model

Multiple liquid-liquid critical points and density anomaly in core-softened potentials

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