Twofold reentrant melting in a double-Gaussian fluid

Prestipino, Santi; Speranza, Cristina; Malescio, G.; Giaquinta, P. V.

doi:10.1063/1.4866897

Cited by 12 publications

(16 citation statements)

References 23 publications

(32 reference statements)

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“…Equation (6) is checked below against the computed BL. Far below η c , the DGM exhibits a liquid-vapor transition for very low ρ and T [10], with a bell-shaped coexistence line whose height and width increase with η [11]. Getting closer to η c , the binodal line undergoes a remarkable modification for low T , where it widens substantially (Fig.…”

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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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confidence: 99%

Phase behavior near and beyond the thermodynamic stability threshold

Malescio

Prestipino

2015

Phys. Rev. E

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“…3, we have also included the melting and freezing points obtained, at various temperatures, through the variational theory introduced in Ref. [15], as well as a number of bcc melting points estimated by the so-called heat-until-it-melts (HUIM) method, also described in Ref. [15] (the degree of solid overheating is 13% near the triple point but much larger-about 23%-at the highest probed pressures).…”

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confidence: 99%

“…[15], as well as a number of bcc melting points estimated by the so-called heat-until-it-melts (HUIM) method, also described in Ref. [15] (the degree of solid overheating is 13% near the triple point but much larger-about 23%-at the highest probed pressures). Qualitatively speaking, the agreement of both approximations with the MC points is fairly good.…”

Section: Resultsmentioning

confidence: 99%

“…Compared to a similar system with a more modest attraction strength [15], there is a unique solid (bcc crystal) phase which always melts into a slightly denser liquid, with a much higher T c /T t ratio of about 6. Hence, there is a whole range of temperatures where, under isothermal compression, the (vapor) system is led to condensate but not to eventually become solid.…”

Section: Discussionmentioning

confidence: 99%

“…We showed in Ref. [15] that, for σ 2 = σ and ξ = 3σ , these conditions jointly lead to a stable DGM system as long as 2 < 0.026315 . For the present study, we have chosen 2 = 0.02 , i.e., 4 times larger than in the previously investigated case; this would now make the critical temperature T c definitely larger than the maximum melting temperature.…”

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confidence: 98%

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Phase behavior of a fluid with a double Gaussian potential displaying waterlike features

et al. 2014

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Pair potentials that are bounded at the origin provide an accurate description of the effective interaction for many systems of dissolved soft macromolecules (e.g., flexible dendrimers). Using numerical free-energy calculations, we reconstruct the equilibrium phase diagram of a system of particles interacting through a potential that brings together a Gaussian repulsion with a much weaker Gaussian attraction, close to the thermodynamic stability threshold. Compared to the purely repulsive model, only the reentrant branch of the melting line survives, since for lower densities solidification is overridden by liquid-vapor separation. As a result, the phase diagram of the system recalls that of water up to moderate (i.e., a few tens of MPa) pressures. Upon superimposing a suitable hard core on the double-Gaussian potential, a further transition to a more compact solid phase is induced at high pressure, which might be regarded as the analog of the ice I-to-ice III transition in water.

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Intermolecular pair potentials and force fields

Sadus

2024

Molecular Simulation of Fluids

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Twofold reentrant melting in a double-Gaussian fluid

Cited by 12 publications

References 23 publications

Phase behavior near and beyond the thermodynamic stability threshold

Phase behavior near and beyond the thermodynamic stability threshold

Phase behavior of a fluid with a double Gaussian potential displaying waterlike features

Intermolecular pair potentials and force fields

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