Locally preferred structure in simple atomic liquids

TL;DR

This paper introduces a numerical method to identify the locally preferred structure in model liquids by minimizing an effective energy that accounts for intra-cluster interactions and environmental effects, revealing an icosahedral structure in Lennard-Jones liquids.

Contribution

It presents a novel approach to determine local structures in liquids by embedding small clusters in a mean-field environment, reducing surface effects without full bulk frustration.

Findings

The locally preferred structure of Lennard-Jones liquid is an icosahedron.

Environmental effects only slightly decrease the stability of the icosahedral cluster.

Boundary conditions influence the ground-state configuration of Lennard-Jones clusters.

Abstract

We propose a method to determine the locally preferred structure of model liquids. This latter is obtained numerically as the global minimum of the effective energy surface of clusters formed by small numbers of particles embedded in a liquid-like environment. The effective energy is the sum of the intra-cluster interaction potential and of an external field that describes the influence of the embedding bulk liquid at a mean-field level. Doing so we minimize the surface effects present in isolated clusters without introducing the full blown geometrical frustration present in bulk condensed phases. We find that the locally preferred structure of the Lennard-Jones liquid is an icosahedron, and that the liquid-like environment only slightly reduces the relative stability of the icosahedral cluster. The influence of the boundary conditions on the nature of the ground-state configuration of Lennard-Jones clusters is also discussed.