Thermodynamic, dynamic, and structural anomalies for shoulderlike potentials

Barraz, Ney M.; Salcedo, Evy; Barbosa, Márcia C.

doi:10.1063/1.3213615

Cited by 50 publications

(55 citation statements)

References 58 publications

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“…non monotonic dependence of the diffusion coefficient with the control parameter, either T , ϕ or P). The relevance of the glassglass transition scenario found here goes beyond the specific SSS potential: The competition between two repulsive length scales and the presence of diffusion anomalies are observed in several different contexts, ranging from soft matter systems [14,25] to silica [16], and complex liquids [26,27,28]. Our work opens a perspective for understanding slow dynamics in these disparate systems.…”

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confidence: 95%

Disconnected Glass-Glass Transitions and Diffusion Anomalies in a Model with Two Repulsive Length Scales

Sperl

Zaccarelli²,

Sciortino³

et al. 2010

Phys. Rev. Lett.

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Building on mode-coupling-theory calculations, we report a novel scenario for multiple glass transitions in a purely repulsive spherical potential: the square-shoulder. The liquid-glass transition lines exhibit both melting by cooling and melting by compression as well as associated diffusion anomalies, similar to the ones observed in water. Differently from all previously investigated models, here for small shoulder widths a glass-glass line is found that is disconnected from the liquid phase. Upon increasing the shoulder width such a glass-glass line merges with the liquid-glass transition lines, featuring two distinct endpoint singularities that give rise to logarithmic decays in the dynamics. These findings can be explained analytically by the interplay of different repulsive length scales. 66.30.jj, 64.70.ph, 64.70.pe In the field of glassy slow dynamics, many experiments and simulations have been inspired in recent years by the modecoupling theory of the glass transition (MCT) [1]. The theory deals with density autocorrelation functions φ q (t) with wave vectors q, and predicts their long-time limits f q . While in the liquid state f q = 0, the glass state is defined by f q > 0. MCT was first applied to the hard-sphere system (HSS) where a liquid-glass transition was identified [2], and confirmed by experiments [3]. In addition to liquid-glass transitions, for certain interactions MCT also predicts glass-glass transitions: In this case an existing first glass state with f 1 q transforms into a second distinct glass state with f 2 q > f 1 q discontinuously. Such glass-glass transitions were predicted for the square-well system (SWS) where the hard-core repulsion is supplemented by a short-ranged attraction [4,5,6]. In the SWS, the first glass state is driven by repulsion like in the HSS and the second glass state is driven by attraction. The competition between these two mechanisms is responsible for the emergence of glass-glass transitions. Such a line of glass-glass transitions extends smoothly a line of liquid-glass transitions into the glass state and terminates in an endpoint singularity. Close to the endpoint singularity the dynamics is ruled by logarithmic relaxation [7]. The predicted logarithmic decays were identified in computer simulations and establish the relevance of endpoint singularities for the description of glassy dynamics [8,9]. A second dynamical anomaly predicted for the SWS concerns a reentrant liquid-glass line that causes melting by cooling [4,5,6]. This prediction of MCT was confirmed by computer simulation [10] and by experiments in colloidal suspensions [11,12].In this work we replace the attractive length scale in the SWS by a second repulsive length scale δ of the squareshoulder system (SSS) as shown in Fig. 1. The SSS can be considered the simplest potential with two competing interparticle distances; it is applied to describe properties of metallic glasses like cerium or cesium [13] In the following, the glass-transition diagrams are calculated from the singularities of ...

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confidence: 95%

Disconnected Glass-Glass Transitions and Diffusion Anomalies in a Model with Two Repulsive Length Scales

Sperl

Zaccarelli²,

Sciortino³

et al. 2010

Phys. Rev. Lett.

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“…Both models present several of the anomalous features of water [14][15][16][17][18][19][20][21][22][23][24][25][26][27]. However, the second kind of model does not involve specific orientation of low-energy pairs of particles: pair energy is controlled by distance, not by orientation.…”

Section: Introductionmentioning

confidence: 99%

Hydration and anomalous solubility of the Bell-Lavis model as solvent

et al. 2012

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We address the investigation of the solvation properties of the minimal orientational model for water originally proposed by [Bell and Lavis, J. Phys. A 3, 568 (1970)]. The model presents two liquid phases separated by a critical line. The difference between the two phases is the presence of structure in the liquid of lower density, described through the orientational order of particles. We have considered the effect of a small concentration of inert solute on the solvent thermodynamic phases. Solute stabilizes the structure of solvent by the organization of solvent particles around solute particles at low temperatures. Thus, even at very high densities, the solution presents clusters of structured water particles surrounding solute inert particles, in a region in which pure solvent would be free of structure. Solute intercalates with solvent, a feature which has been suggested by experimental and atomistic simulation data. Examination of solute solubility has yielded a minimum in that property, which may be associated with the minimum found for noble gases. We have obtained a line of minimum solubility (TmS) across the phase diagram, accompanying the line of maximum density. This coincidence is easily explained for noninteracting solute and it is in agreement with earlier results in the literature. We give a simple argument which suggests that interacting solute would dislocate TmS to higher temperatures.

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“…Particles changing from the one length scale to the other is the characteristic of the density anomaly. [26,[50][51][52].…”

Section: B µV T Ensemble (Gcmc)mentioning

confidence: 99%

Critical points, phase transitions and water-like anomalies for an isotropic two length scale potential with increasing attractive well

Pinheiro

Furlan

Krott

et al. 2017

Physica A: Statistical Mechanics and its Applications

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Molecular Dynamic and Monte Carlo studies are performed in a family of core-softened (CS) potential, composed by two length scales: a repulsive shoulder at short distances and the another a variable scale, that can be repulsive or strongly attractive depending on the parameters used.The density, diffusion and structural anomalous regions in the pressure versus temperature phase diagram shrink in pressure as the system becomes more attractive. The liquid-liquid transition appears as a consequence of the non monotonic behavior of the density versus pressure isotherms with the increase of the attraction well. We found that the liquid-gas phase transition is Ising-like for all the CS potentials and its critical temperature increases with the increase of the attraction. No Ising-like behavior for the liquid-liquid phase transition was detected in the Monte Carlo simulations what might be due to the presence of stable solid phases.

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Thermodynamic, dynamic, and structural anomalies for shoulderlike potentials

Cited by 50 publications

References 58 publications

Disconnected Glass-Glass Transitions and Diffusion Anomalies in a Model with Two Repulsive Length Scales

Disconnected Glass-Glass Transitions and Diffusion Anomalies in a Model with Two Repulsive Length Scales

Hydration and anomalous solubility of the Bell-Lavis model as solvent

Critical points, phase transitions and water-like anomalies for an isotropic two length scale potential with increasing attractive well

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