The recently proposed method for modulating through an external field the composition of a binary fluid mixture adsorbed in a slit pore is discussed. The population inversion near the bulk (demixing) instability is first analyzed in the case of a symmetric mixture of nonadditive hard spheres, without field. It is next investigated for a mixture comprising dipolar particles subject to an external field. The influence of several factors on the adsorption curves including bulk composition, pore width, field direction, polarizability versus permanent dipoles, and temperature on this field induced population inversion is shown by Monte Carlo simulation.

Starting from a generic model of a pore/bulk mixture equilibrium, we propose a novel method for modulating the composition of the confined fluid without having to modify the bulk state. To achieve this, two basic mechanisms-sensitivity of the pore filling to the bulk thermodynamic state and electric field effect-are combined. We show by Monte Carlo simulation that the composition can be controlled both in a continuous and in a jumpwise way. Near the bulk demixing instability, we demonstrate a field induced population inversion in the pore. The conditions for the realization of this method should be best met with colloids, but being based on robust and generic mechanisms, it should also be applicable to some molecular fluids.

In this paper we study the structure of highly confined mixtures of polar and nonpolar macroparticles in an external field by Monte Carlo simulation in the canonical ensemble. Without attempting a systematic investigation of the model, several effects including confinement, polarization, and solvation forces are considered. In particular, we show that layering at different length scales can be obtained in mixtures of differently sized particles subject to an external electric field.

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simulation of confined fluids of polarizable particles:an efficient iterative treatment of the local field in slab geometry using Ewald summation. Molecular Physics, Taylor Francis, 2010, 108 (13) We propose a method for treating in Monte Carlo simulations the problem of the induced dipoles for polarizable particles fluids confined in slab geometry and subject to an external field. In order to compute the local field in a reasonable time, a partial update of the induced dipole moments is performed by introducing a cut-off distance, as in bulk systems. This strategy is then combined with a slab adapted 3D-Ewald summation for treating the longrange interactions between the induced dipoles. The method is illustrated by simulations of confined binary mixtures in the canonical and grand canonical ensembles.