Phase stability of binary non-additive hard-sphere mixtures: A self-consistent integral equation study

Abstract

Phase separation in mixtures of a rodlike colloid and two or more rodlike polymersWe have tested the capabilities of a new self-consistent integral equation, closely connected with Verlet's modified closure, for the study of fluid-fluid phase separation in symmetric non-additive hard-sphere mixtures. New expressions to evaluate the chemical potential of mixtures are presented and play a key role in the construction of the phase diagram. The new integral equation, which implements consistency between virial and fluctuation theorem routes to the isothermal compressibility, together with chemical potential and virial pressure consistency via the Gibbs-Duhem relation, yields a phase diagram which especially at high densities agrees remarkably well with the new semi-Grand Ensemble Monte Carlo simulation data also presented in this work. Deviations close to the critical point can be understood as a consequence of the inability to enforce virial-fluctuation consistency in the neighborhood of the spinodal decomposition curve.

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

“…More general instances of the non-additive hard sphere mixture problem (mostly in the symmetric case) have been studied in the two-dimensional limit, 21 and in a number of detailed studies in three dimensions. [22][23][24][25] Duda and coworkers 26 carried out a simulation and mean field study of the influence of confinement of the critical properties of the NAHS mixture and obtained results which turned out to be in qualitative agreement with those of Góźdź for the WR system: 20 confinement by neutral walls in slit pores stabilizes mixing in a pure athermal system such as the NAHS mixture.…”

“…In addition to the conventional MC moves, particles can also modify their identity (i.e., the species to which they belong). 22 The identity sampling can be performed through an efficient cluster algorithm that involves all the particles in the systems and that will be presented later in the paper. After 5 × 10 5 MC sweeps for equilibration, our simulations were typically extended over 2 × 10 6 MC sweeps to perform averages.…”

Instability of a fluid–fluid interface in driven colloidal mixtures

“…For a positive and vanishing external drive, our system will lead to equilibrium fluid-fluid phase separation including a critical point which has been studied in non-additive hard core models by means of theory and simulation; see e.g. [32][33][34][35][36][37]. We emphasize that our dynamics is overdamped motion and there is no inertia.…”

On the triplet structure of binary liquids

“…24 The pair distribution functions obtained both from simulation and theory are depicted in Fig. 1, which illustrates the reliability of the theory used on the pair particle level.…”