Density fluctuations and field mixing in the critical fluid

Wilding, Nigel B.; Bruce, Ann

doi:10.1088/0953-8984/4/12/008

Cited by 236 publications

(263 citation statements)

References 37 publications

(2 reference statements)

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“…Histogram reweighting techniques 12,13 are then used to blend histograms and to generate binodal curves. Apparent critical parameters for a given box size are estimated by means of mixed-field finite-size scaling techniques 14,15 assuming that the criticality of the systems investigated here belongs to the Ising universality class. Figure 1 shows simulated binodal curves for asymmetric ionic systems.…”

Section: Models and Simulation Methodsmentioning

confidence: 99%

Phase equilibria and clustering in size-asymmetric primitive model electrolytes

Yan

Pablo

2001

The Journal of Chemical Physics

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The low-temperature phase coexistence of size-asymmetric primitive model electrolyte solutions has been investigated by means of Monte Carlo simulations. A multidimensional parallel tempering method is employed and results are analyzed by means of histogram reweighting. Coexistence curves and critical constants are determined as a function of size asymmetry, ϭ ϩ / Ϫ , from 0.05 to 1. It is found that the critical temperature and the critical density decrease as decreases. These trends appear to contradict available integral-equation theoretical predictions. For highly asymmetric systems, we report the formation of large chain-like and ring-like structures. These clusters are much larger than those observed in symmetric electrolytes, and they are shown to give rise to considerable finite-size effects.

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Section: Models and Simulation Methodsmentioning

confidence: 99%

Phase equilibria and clustering in size-asymmetric primitive model electrolytes

Yan

Pablo

2001

The Journal of Chemical Physics

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“…19 These techniques are also used to determine the binodal curve for the systems of interest. Mixed-field finitesize scaling methods [20][21][22] are employed to locate the precise coordinates of the critical solution point. Figure 1 shows the binodal curve for a nϭ20 bondfluctuation model chain.…”

Section: Models and Simulation Methodsmentioning

confidence: 99%

Critical behavior of lattice polymers studied by Monte Carlo simulations

Yan

Pablo

2000

The Journal of Chemical Physics

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A newly developed expanded grand-canonical formalism is applied to locate the critical point of systems of long polymeric molecules. Two polymer systems are investigated in this work; the first consists of chains in a simple cubic lattice, the second consists of bond-fluctuating molecules. For the former we simulate molecules of up to 16 000 sites, and for the latter we study molecules of up to 500 sites. These chain lengths are well above those investigated by all prior simulation studies of critical phenomena in polymer solutions. Critical parameters are determined as a function of chain length by means of field-mixing finite-size scaling techniques. Our results for the scaling behavior of the critical temperature are consistent with literature values. Our results for the scaling of the critical density, however, indicate that the corresponding critical exponent is higher than that reported by previous authors. The leading logarithmic term of the finite-chain-length correction to the critical density is confirmed by our results.

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“…The box side is L = 14 for T > 0.055 and L = 22.2 otherwise. We use the standard Bruce-Wilding method to pinpoint the location of the critical points [36]. In order to properly estimate the lower critical parameters we join several P (ρ, U ) computed at different T by implementing the multiplehistogram reweighting method [37].…”

Section: Pacs Numbersmentioning

confidence: 99%

Self-Assembly in Chains, Rings, and Branches: A Single Component System with Two Critical Points

2013

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We study the interplay between phase separation and self-assembly in chains, rings and branched structures in a model of particles with dissimilar patches. We extend Wertheim's first order perturbation theory to include the effects of ring formation and theoretically investigate the thermodynamics of the model. We find a peculiar shape for the vapor-liquid coexistence, featuring re-entrant behavior in both phases and two critical points, despite the single-component nature of the system. The emergence of the lower critical point is caused by the self-assembly of rings taking place in the vapor, generating a phase with lower energy and lower entropy than the liquid. Monte Carlo simulations of the same model fully support these unconventional theoretical predictions. PACS numbers:Understanding the competition between self-assembly and phase-separation is central in today's research in different fields encompassing biology, soft-matter, material science, statistical mechanics. Self-assembly of finitesize aggregates requires strong interaction energies compared to the thermal energy to guarantee that the generated structure is persistent. As a result, self-assembly competes with the ubiquitous macroscopic phase separation, the low-temperature tendency common to atoms, molecules and larger particles to maximize the number of bonded neighbours and minimize the potential energy, giving rise to a condensed (liquid) state [1]. When particles can arrange themselves into low energy and weakly interacting finite size aggregates, self-assembly can completely suppress phase separation [2][3][4]. Soft matter and biology offers several examples of three-dimensional stable aggregates (e.g. micelles, vesicles, capsids [5,6]) which constitute the stable phase in wide temperature and density regions.The possibility of hampering the formation of large amorphous aggregates in favor of ordered structures is often facilitated by the presence of strong, directional and saturable interactions (limited valence) [7][8][9]. The renewed focus on the role of directional interactions, stimulated by the synthesis of new-generation patchy colloids [10][11][12][13], has deepened our understanding not only of the role of the valence on the gas-liquid phase separation [14] but also on the competition between selfassembly and phase separation. Two recent investigations have provided insights particularly relevant for this work: (i) a numerical study of Janus colloids in which a gas-liquid critical point and a self-assembly process are simultaneously observed [15,16]. In this model, the formation of energetically stable vesicles stabilizes at low temperature T the gas-phase; (ii) a study of particles with dissimilar patches [17][18][19], promoting respectively chaining and branching, specifically designed to reproduce a mean-field model introduced by Safran and Tlustly [20] to describe the phase behavior of dipolar fluids. Here branching produces a gas-liquid critical point, but on cooling the formation of energetically favored chains stabilizes, thi...

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Density fluctuations and field mixing in the critical fluid

Cited by 236 publications

References 37 publications

Phase equilibria and clustering in size-asymmetric primitive model electrolytes

Phase equilibria and clustering in size-asymmetric primitive model electrolytes

Critical behavior of lattice polymers studied by Monte Carlo simulations

Self-Assembly in Chains, Rings, and Branches: A Single Component System with Two Critical Points

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