Triplet Correlations Dominate the Transition from Simple to Tetrahedral Liquids

Singh, Murari; Dhabal, Debdas; Nguyen, Andrew H.; Molinero, Valeria; Chakravarty, Charusita

doi:10.1103/physrevlett.112.147801

Cited by 43 publications

(43 citation statements)

References 51 publications

(92 reference statements)

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“…135,147,329−332 As a function of increasing tetrahedrality, the triplet contribution to the excess entropy is significantly higher than the pair-entropy contribution. 333 Transformation to a triplet-dominated fluid strongly favors the formation of a tetrahedral crystal as well as the existence of a heat capacity anomaly, and the local order within the first neighbor shell is a critical factor in determining the behavior upon supercooling. The characteristic rise in heat capacity on the isobaric cooling of tetrahedral liquids is closely tracked by the pair and triplet contributions to the entropy (see Figure 22) and thus provides a direct connection between structural correlations and thermodynamics.…”

Section: Relation Between Dynamics and Thermodynamicsmentioning

confidence: 99%

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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: Relation Between Dynamics and Thermodynamicsmentioning

confidence: 99%

“…The total (C P ), pair (C 2 ), and triplet (C 3 ) contributions as a function of temperature ( T ) for the monatomic water (mW) model at 1 atm pressure. Reproduced with permission from ref (333). Copyright 2014 American Institute of Physics.…”

Section: Relation Between Dynamics and Thermodynamicsmentioning

confidence: 99%

Water: A Tale of Two Liquids

et al. 2016

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“…The stable crystalline phases of mW water are the same as the ones of silicon: clathrates at negative pressures, hexagonal and cubic ice (equivalent to dh and dc) at intermediate pressures, and the sc16 crystal at high pressures. The melting temperatures are higher, signaling that the liquid structure changes with the increased directionality of the interaction, a point which has been addressed very recently [43].…”

Section: Phase Diagram Of Mw Watermentioning

confidence: 99%

Novel stable crystalline phase for the Stillinger-Weber potential

2014

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Tetrahedral liquids such as silicon, germanium, carbon, water, and silica are an important class of materials not only for industrial applications but also for our understanding of nature. The Stillinger-Weber potential is one of the most popular models for computer simulations of these systems with tetrahedral coordination, with the directionality of the interactions introduced via a three-body repulsive term which promotes locally tetrahedral arrangements. This approach has been extended to various tetrahedral liquids, providing valuable insight into the physics of group XIV elements and more recently water. Perhaps surprisingly, a consistent thermodynamic picture of this class of models is still lacking despite their widespread usage. Here we fill this gap by computing equilibrium phase diagrams for the silicon and water parametrizations and report a novel crystal structure which dominates the models' phase diagram at intermediate and high pressure, and thus warrants further theoretical and numerical investigation. Our results redefine the phase behavior of an important class of tetrahedrally coordinated systems, and also suggest that a more stringent test for simulation models is the ability to select the experimentally relevant crystalline phases, as opposed to just reproducing their mechanical stability.

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“…The elements of the representation in terms of Q-valued maps are, in contrast, strongly coupled. By looking at atomistic descriptions, we mention that the Stillinger-Weber potential for covalently bonded systems is made by two terms plus permutations of the second one (see, for example, [63]). …”

Section: Examplesmentioning

confidence: 99%