The penetrable square-well model: extensive versus non-extensive phases

Fantoni, Riccardo; Malijevský, Alexandr; Santos, Andrés; Giacometti, Andrea

doi:10.1080/00268976.2011.597357

Cited by 13 publications

(11 citation statements)

References 33 publications

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“…As η c is approached from the stable side, the liquid-vapor region undergoes an anomalous widening at low temperature, until the liquid density diverges for T → 0 at η = η c [10,11]. Inspired by previous observations by Fantoni and coworkers [12,13], we have also analyzed the homogeneous fluid beyond the threshold, finding that a sharp line divides the thermodynamic plane in two regions, characterized by radically different collapsing behaviors: on one side of the line (i.e., for high densities) collapse occurs extremely fast ("strongly-unstable" regime), whereas on the other side (low densities) the waiting time for collapse enormously exceeds typical simulation time ("weakly-unstable" regime).…”

Section: Ruelle and Fisher Have Devised A Few Simple Criteria To Checmentioning

confidence: 94%

Universal behavior of soft-core fluids near the threshold of thermodynamic stability

Malescio

Parola

Prestipino

2018

The Journal of Chemical Physics

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We study, by using liquid-state theories and Monte Carlo simulation, the behavior of systems of classical particles interacting through a finite pair repulsion supplemented with a longer range attraction. Any such potential can be driven Ruelle-unstable by increasing the attraction at the expense of repulsion, until the thermodynamic limit is lost. By examining several potential forms, we find that all systems exhibit a qualitatively similar behavior in the fluid phase as the threshold of thermodynamic stability is approached (and possibly surpassed). The general feature underlying the approach to Ruelle instability is a pronounced widening of the liquid-vapor binodal (and spinodal) line at low temperatures, to such an extent that at the stability threshold a vanishing-density vapor would coexist with a diverging-density liquid. We attempt to rationalize the universal pathway to Ruelle instability in soft-core fluids by appealing to a heuristic argument.

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Section: Ruelle and Fisher Have Devised A Few Simple Criteria To Checmentioning

confidence: 94%

Universal behavior of soft-core fluids near the threshold of thermodynamic stability

Malescio

Parola

Prestipino

2018

The Journal of Chemical Physics

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“…In Refs. [8,9] it was suggested that the unstable regime might actually be composed of two regions, a strongly-unstable region where the phase of the system is non-extensive, and a weakly-unstable region where the system is, to all practical purposes, stable.…”

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confidence: 99%

Phase behavior near and beyond the thermodynamic stability threshold

Malescio

Prestipino

2015

Phys. Rev. E

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The phase behavior of stabilized dispersions of macromolecules is most easily described in terms of the effective interaction between the centers of mass of solute particles. For molecules such as polymer chains, dendrimers, etc., the effective pair potential is finite at the origin, allowing "particles" to freely interpenetrate each other. Using a double-Gaussian model (DGM) for demonstration, we study the behavior of the system as a function of the attraction strength η. Above a critical strength η(c), the infinite-size system is Ruelle unstable, in that it collapses to a cluster of finite volume. As η(c) is approached from below, the liquid-vapor region exhibits an anomalous widening at low temperature, and the liquid density apparently diverges at the stability threshold. Above η(c), the thermodynamic plane is divided in two regions, differing in the value of the average waiting time for collapse, being finite and small on one side of the boundary line, while large or even infinite in the other region. Upon adding a small hard core to the DGM potential, stability is fully recovered and the boundary line is converted to the spinodal line of a transition between fluid phases. We argue that the destabilization of a colloidal dispersion, as induced by the addition of salt or other flocculant, finds a suggestive analogy in the process by which a strengthening of the attraction pushes a stabilized-DGM system inside the fluid-fluid spinodal region.

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“…In constructing the interpolant, we used the fact that the first three of these quantities are zero at ρ = 0. To evaluate f 2 (T, ρ = 0), we used the expression for g r (r) in the low density limit in Equation (8). Under the random phase approximation, this gives lim ρ→0 c(r) = e −βφ r (r) − 1 − βφ a (r).…”

Section: Numerical Proceduresmentioning

confidence: 99%

“…The penetrable square well potential, a bounded version of square well potential, is the simplest model that exhibits vapour-liquid coexistence [6][7][8]. To study interfacial phenomena by means of DPD, Liu et al [9] introduced a penetrable potential function constructed from cubic spline functions.…”

Section: Introductionmentioning

confidence: 99%

Equilibrium properties of penetrable soft spheres

Kusaka

Jia

2020

Molecular Physics

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Using the Weeks-Chandler-Andersen separation scheme, we explored equilibrium properties of fully penetrable soft spheres with an attractive tail. When the radial distribution function of the reference system is computed by means of the integral equation theory using the hyper-netted-chain closure, this separation scheme predicts pressure-density isotherms, vapour-liquid phase coexistence, and surface tension in good agreement with the results from Monte Carlo simulations even though the attractive portion of the interparticle potential has a significant effect on the radial distribution function. Despite its simplicity, the model potential we studied, with a certain parameter value, exhibits a non-monotonic temperature dependence of the liquid phase density over a wide range of pressure.

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The penetrable square-well model: extensive versus non-extensive phases

Cited by 13 publications

References 33 publications

Universal behavior of soft-core fluids near the threshold of thermodynamic stability

Universal behavior of soft-core fluids near the threshold of thermodynamic stability

Phase behavior near and beyond the thermodynamic stability threshold

Equilibrium properties of penetrable soft spheres

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