Fluid - solid transition in simple systems using density functional theory

TL;DR

This paper uses a density functional theory approach to study the fluid-solid transition in systems with Lennard-Jones potentials, showing good agreement with simulations and emphasizing the importance of symmetry-broken contributions.

Contribution

It introduces a free energy functional incorporating both symmetry-conserved and symmetry-broken parts to analyze fluid-solid transitions in Lennard-Jones systems.

Findings

The theoretical freezing parameters agree well with simulation data.

Symmetry-broken contributions are crucial for stabilizing the crystalline phase.

The attractive part of the Lennard-Jones potential has a minor effect on freezing parameters.

Abstract

A free energy functional for a crystal proposed by Singh and Singh (Europhysics Letters \textbf{88}, 16005 (2009)) which contains both the symmetry-conserved and symmetry-broken parts of the direct pair correlation function has been used to investigate the fluid-solid transition in systems interacting via purely repulsive WCA Lennard - Jones (RLJ) potential and the full Lennard - Jones (LJ) potential. The results found for freezing parameters for the fluid - face centred cubic (fcc) crystal transition are in very good agreement with simulation results. It is shown that although the contribution made by the symmetry broken part to the grand thermodynamic potential at the freezing point is small compared to that of the symmetry conserving part, its role is crucial in stabilizing the crystalline structure and on values of freezing parameters. The effect of attractive part of the LJ potential on the freezing parameters is found to be small, confirming the view that the fluid - solid transition is primarily determined by the repulsive part of the potential.