Density functional theory for nearest-neighbor exclusion lattice gasses in two and three dimensions

TL;DR

This paper develops a density functional theory incorporating dimensional crossover for lattice gases with nearest-neighbor exclusion, connecting systems across various lattice types and dimensions, and derives their phase diagrams.

Contribution

It introduces a unified density functional framework that captures dimensional crossover for lattice gases, extending fundamental measure theory to multiple lattice geometries.

Findings

Derived functionals for various lattice geometries.

Obtained bulk phase diagrams for all systems.

Established connections between different lattice models.

Abstract

To speak about fundamental measure theory obliges to mention dimensional crossover. This feature, inherent to the systems themselves, was incorporated in the theory almost from the beginning. Although at first it was thought to be a consistency check for the theory, it rapidly became its fundamental pillar, thus becoming the only density functional theory which possesses such a property. It is straightforward that dimensional crossover connects, for instance, the parallel hard cube system (three-dimensional) with that of squares (two-dimensional) and rods (one-dimensional). We show here that there are many more connections which can be established in this way. Through them we deduce from the functional for parallel hard (hyper)cubes in the simple (hyper)cubic lattice the corresponding functionals for the nearest-neighbor exclusion lattice gases in the square, triangular, simple cubic, face-centered cubic, and body-centered cubic lattices. As an application, the bulk phase diagram for all these systems is obtained.