Relation between the transport coefficients and the internal entropy of simple systems

Rosenfeld, Yaakov

doi:10.1103/physreva.15.2545

Cited by 599 publications

(645 citation statements)

References 33 publications

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“…The results presented here represent, to our knowledge, the first evidence that ex s , which provides a scaling for the diffusivity of simple equilibrium fluids [3][4][5][6] , also captures supercooled liquid dynamics. Moreover, since ex s is a standard thermodynamic quantity that can be approximated based on structural data from, e.g., scattering experiments 19 , it also promises to provide the elusive link between structure and dynamics 20 of the liquid state.…”

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confidence: 89%

“…As a result, it cannot provide a comprehensive description of liquid-state diffusivity. On the other hand, the excess entropy, a fundamental thermodynamic quantity which captures the correlations between particles due to their finite volumes and mutual interactions, does capture the diffusivity of equilibrium fluids [3][4][5][6] . If excess entropy turns out to also describe supercooled liquid dynamics, which is the issue we investigate here via computer simulations, then the relationship between thermodynamics and dynamics will be much simpler than previously anticipated.…”

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confidence: 99%

“…We first examine the behavior of a "core-softened" fluid 15 that belongs to a larger class of model potentials known to reproduce many of liquid water's distinctive 3 properties 15,16 .…”

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confidence: 99%

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Relationship between thermodynamics and dynamics of supercooled liquids

Mittal

Errington

Truskett

2006

The Journal of Chemical Physics

108

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Diffusivity, a measure for how rapidly a fluid self-mixes, shows an intimate, but seemingly fragmented, connection to thermodynamics. On one hand, the "configurational" contribution to entropy (related to the number of mechanically-stable configurations that fluid molecules can adopt) has long been considered key for predicting supercooled liquid dynamics near the glass transition. On the other hand, the excess entropy (relative to ideal gas) provides a robust scaling for the diffusivity of fluids above the freezing point. Here we provide, to our knowledge, the first evidence that excess entropy also captures how supercooling a fluid modifies its diffusivity, suggesting that dynamics, from ideal gas to glass, is related to a single, standard thermodynamic quantity.Comment: to appear in Journal of Chemical Physic

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Relationship between thermodynamics and dynamics of supercooled liquids

Mittal

Errington

Truskett

2006

The Journal of Chemical Physics

108

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“…As the number of molecular layers decreases and the system becomes more two-dimensional, the configurational entropy and diffusivity of the film decrease while the viscosity increases. Although the experimental observation of a viscosity change that is not accompanied by a temperature or density change is very unusual, the direct relationship between entropy and the kinetic properties of a bulk or confined fluid is not a new concept [42][43][44]. Thus, it is reasonable to conclude that the viscosity increase that accompanies confinement is a result of decreasing entropy and not molecular packing, and that confined OMCTS is approaching a jammed state.…”

Section: H Y S I C a L R E V I E W L E T T E R Smentioning

confidence: 95%

Density and Phase State of a Confined Nonpolar Fluid

Kienle

Kuhl

2016

Phys. Rev. Lett.

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Measurements of the mean refractive index of a spherelike nonpolar fluid, octamethytetracylclosiloxane (OMCTS), confined between mica sheets, demonstrate direct and conclusive experimental evidence of the absence of a first-order liquid-to-solid phase transition in the fluid when confined, which has been suggested to occur from previous experimental and simulation results. The results also show that the density remains constant throughout confinement, and that the fluid is incompressible. This, along with the observation of very large increases (many orders of magnitude) in viscosity during confinement from the literature, demonstrate that the molecular motion is limited by the confining wall and not the molecular packing. In addition, the recently developed refractive index profile correction method, which enables the structural perturbation inherent at a solid-liquid interface and that of a liquid in confinement to be determined independently, was used to show that there was no measurable excess or depleted mass of OMCTS near the mica surface in bulk films or confined films of only two molecular layers.

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“…To summarize, the excess entropy has for a long time been used to describe the relaxation time of liquids 45,60 and more recently shown to work also for confined systems 33 . We demonstrated above a new controlling variable, the excess isochoric heat capacity, which is expected to apply for the fairly large class of liquids with strong correlations between virial and potential energy fluctuations in the NVT ensemble.…”

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confidence: 99%

Predicting How Nanoconfinement Changes the Relaxation Time of a Supercooled Liquid

et al. 2013

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The properties of nanoconfined fluids can be strikingly different from those of bulk liquids. A basic unanswered question is whether the equilibrium and dynamic consequences of confinement are related to each other in a simple way. We study this question by simulation of a liquid comprising asymmetric dumbbell-shaped molecules, which can be deeply supercooled without crystallizing. We find that the dimensionless structural relaxation times − spanning six decades as a function of temperature, density, and degree of confinement − collapse when plotted versus excess entropy. The data also collapse when plotted versus excess isochoric heat capacity, a behaviour that follows from the existence of isomorphs in the bulk and confined states.That confined liquids microscopically relax and flow with different characteristic time scales than bulk liquids is hardly surprising. Confining boundaries bias the spatial distribution of the constituent molecules and the ways by which those molecules can dynamically rearrange. These effects play important roles in the design of coating, nanopatterning, and nanomanufacturing technologies 1,2 . As a result, they have already been experimentally characterized for a wide variety of material systems, including small-molecule fluids 3-10 , polymers 11-16 , ionic liquids 17 , liquid crystals 18 , and dense colloidal suspensions [19][20][21][22][23] , and studied extensively via molecular simulations 22,24-31 . Recent reviews of confined-liquid behavior may be found in, e.g., Refs. 10,32 .Unfortunately, successful theories for predicting the dynamics of inhomogeneous fluids have been slower to emerge. Here, we explore the possibility of a novel approach for predicting how confinement affects the dynamics of viscous fluids. The central idea is motivated by the observation from molecular simulations that, under equilibrium conditions, key dimensionless "reduced" quantities for confined fluids closely correspond to those of homogeneous bulk fluids with the same excess entropy 33-37 (relative to an ideal gas at the same density and temperature). The excess entropy can be computed using Monte Carlo methods 36 or predicted from classical density-functional theories 35,38 . An open question is whether this observed correspondence between dynamics and excess entropy applies for fluids in deeply supercooled liquid states approaching the glass transition, where highly nontrivial dynamic effects of confinement are observed. Another open question is whether thermodynamic properties other than the excess entropy can be used to predict the dynamics in confinement.To investigate these questions we study the behavior of a glass-former comprising asymmetric dumbbell-shaped molecules 39 . This model is perhaps the simplest singlecomponent system that avoids freezing upon cooling or compression in confinement, allowing for a systematic comparison of the properties of supercooled states in both bulk and confined geometries. The latter is modeled as a slit-pore, i.e., a sandwich geometry, using a 9-3 LennardJo...

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Relation between the transport coefficients and the internal entropy of simple systems

Cited by 599 publications

References 33 publications

Relationship between thermodynamics and dynamics of supercooled liquids

Relationship between thermodynamics and dynamics of supercooled liquids

Density and Phase State of a Confined Nonpolar Fluid

Predicting How Nanoconfinement Changes the Relaxation Time of a Supercooled Liquid

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