Demixing and confinement of non-additive hard-sphere mixtures in slit pores

Abstract

Using Monte Carlo simulation, we study the influence of geometric confinement on demixing for a series of symmetric non-additive hard spheres mixtures confined in slit pores. We consider both a wide range of positive non-additivities and a series of pore widths, ranging from the pure two dimensional limit to a large pore width where results are close to the bulk three dimensional case. Critical parameters are extracted by means of finite size analysis. As a general trend, we find that for this particular case in which demixing is induced by volume effects, the critical demixing densities (and pressures) increase due to confinement between neutral walls, following the expected behavior for phase equilibria of systems confined by pure repulsive walls: i.e., confinement generally enhances miscibility. However, a non-monotonous dependence of the critical pressure and density with pore size is found for small non-additivities. In this latter case, it turns out that an otherwise stable bulk mixture can be unexpectedly forced to demix by simple geometric confinement when the pore width decreases down to approximately one and a half molecular diameters. C 2015 AIP Publishing LLC. [http://dx

Disordered hyperuniformity in two-component nonadditive hard-disk plasmas

“…In the vicinity of the demixing transition which occurs for positive non-additivity of the disks we performed semi-grand canonical MC simulations along the lines detailed in Ref. [30] for the plain NAHD system. In particular, we took advantage of the cluster algorithm de-scribed in Ref.…”

“…In particular, we took advantage of the cluster algorithm de-scribed in Ref. [30] for identity sampling. Two particles of the same species are considered linked within the same cluster when their separation is less than σ(1 + ∆).…”

“…Two particles of the same species are considered linked within the same cluster when their separation is less than σ(1 + ∆). With this choice cluster identity swaps do not lead to particle overlaps and for the present symmetrical case where the chemical potential difference ∆µ = µ A −µ B = 0, the procedure leads to a rejection free algorithm of composition sampling for a fixed set of particle positions [30].…”

“…In Ref. [30], it was found that the uncharged system exhibits a phase separation when ∆ = 0.2 with a conso- lute point at ρ c σ 2 = 0.69 (and obviously x 1 = x 2 = 1/2). We have first studied the system at a somewhat lower total density, ρσ 2 = 0.60 and a relatively large Coulombic coupling, Γ = 5.…”

Disordered multihyperuniformity derived from binary plasmas

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