Dynamical density functional theory: phase separation in a cavity and the influence of symmetry

TL;DR

This paper uses dynamical density functional theory to study how symmetry breaking in external potentials influences phase separation in a binary fluid confined in a cavity, revealing that symmetry breaking can induce phase separation.

Contribution

It demonstrates how breaking external potential symmetry affects phase separation dynamics in a binary fluid using dynamical density functional theory.

Findings

Symmetry constrains density profiles to be identical for both species.

Breaking symmetry allows phase separation to manifest in density profiles.

External potential symmetry influences phase behavior in confined binary fluids.

Abstract

Consider a fluid composed of two species of particles, where the interparticle pair potentials $u_{11} = u_{22} \neq u_{12}$. On confining an equal number of particles from each species in a cavity, one finds that the average one body density profiles of each species are constrained to be exactly the same due to the symmetry, when both external cavity potentials are the same. For a binary fluid of Brownian particles interacting via repulsive Gaussian pair potentials that exhibits phase separation, we study the dynamics of the fluid one body density profiles on breaking the symmetry of the external potentials, using the dynamical density functional theory of Marconi and Tarazona [{\it J. Chem. Phys.}, {\bf 110}, 8032 (1999)]. On breaking the symmetry we see that the fluid one body density profiles can then show the phase separation that is present.