Locally preferred structure in simple atomic liquids

摘要

We propose a method to determine the locally preferred structure of modelliquids. This latter is obtained numerically as the global minimum of theeffective energy surface of clusters formed by small numbers of particlesembedded in a liquid-like environment. The effective energy is the sum of theintra-cluster interaction potential and of an external field that describes theinfluence of the embedding bulk liquid at a mean-field level. Doing so weminimize the surface effects present in isolated clusters without introducingthe full blown geometrical frustration present in bulk condensed phases. Wefind that the locally preferred structure of the Lennard-Jones liquid is anicosahedron, and that the liquid-like environment only slightly reduces therelative stability of the icosahedral cluster. The influence of the boundaryconditions on the nature of the ground-state configuration of Lennard-Jonesclusters is also discussed.