Extended dynamical density functional theory for nonisothermal binary systems including momentum density

TL;DR

This paper develops an extended dynamical density functional theory (EDDFT) for nonisothermal binary systems, incorporating momentum and energy densities to accurately describe diffusive and convective dynamics at a microscopic level.

Contribution

The paper introduces a novel EDDFT that includes momentum and energy densities, enabling a comprehensive microscopic description of nonisothermal two-phase flows.

Findings

Derived an exact entropy and free-energy functional for hard spheres.

Demonstrated that EDDFT captures correct speed of sound.

Connected EDDFT to mode-coupling theory of glass transition.

Abstract

In order to describe the nonisothermal dynamics of two-phase flows or binary mixtures such as colloidal suspensions consisting of colloidal particles and solvent on a microscopic level, we derive a new extended dynamical density functional theory (EDDFT) that includes the total mass density, the local concentration of one species, the total momentum density, and the energy density as variables using the Mori-Zwanzig-Forster projection operator technique. Through the incorporation of the momentum density into EDDFT, not only the diffusive but also the convective dynamics is taken into account. We derive an exact entropy and free-energy functional for the case of hard spheres. The hydrodynamic limit of our new EDDFT and its relation to the mode-coupling theory of the glass transition are discussed. It is shown that EDDFT allows to obtain the correct value for the speed of sound.