Universality classes and critical phenomena in confined liquid systems

TL;DR

This paper reviews the universal behavior of confined liquid systems near critical points, emphasizing the effects of geometry, boundary conditions, and spatial dispersion, and proposes a Kawasaki-like approach for smooth dimensional crossover.

Contribution

It introduces a Kawasaki-like approach to model the 3D to 2D crossover in critical phenomena of confined liquids, aligning theoretical predictions with experimental data.

Findings

Correct nonzero diffusion coefficient at critical point.

Good agreement between theory and computer simulations for size-dependent critical temperature.

Analysis of neutron scattering in aquatic membrane suspensions.

Abstract

It is well known that the similar universal behavior of infinite-size (bulk) systems of different nature requires the same basic conditions: space dimensionality; number components of order parameter; the type (short- or long-range) of the intermolecular interaction; symmetry of the fluctuation part of thermodynamical potential. Basic conditions of similar universal behavior of confined systems needs the same supplementary conditions such as the number of monolayers for a system confinement; low crossover dimensionality, i.e., geometric form of restricted volume; boundary conditions on limiting surfaces; physical properties under consideration. This review paper is aimed at studying all these conditions of similar universal behavior for diffusion processes in confined liquid systems. Special attention was paid to the effects of spatial dispersion and low crossover dimensionality. This allowed us to receive receiving correct nonzero expressions for the diffusion coefficient at the critical point and to take into account the specific geometric form of the confined liquid volume. The problem of 3D \Leftrightarrow 2D dimensional crossover was analyzed. To receive a smooth crossover for critical exponents, the Kawasaki-like approach from the theory of mode coupling in critical dynamics was proposed. This ensured a good agreement between data of computer experiment and theoretical calculations of the size dependence of the critical temperature T_{c}(H) of water in slitlike pores. The width of the quasi-elastic scattering peak of slow neutrons near the structural phase transition in the aquatic suspensions of plasmatic membranes (mesostructures with the typical thickness up to 10 nm) was studied.