Comparison between icosahedral, decahedral and crystalline Lennard-Jones models containing 500 to 6000 atoms

Abstract

This paper presents a number of models made of soft spheres freely relaxed through the Lennard-Jones potential, in the size range 500 < N < 6000 atoms. The external shape and potential energy of several icosahedral, decahedral and crystalline models are reported. Starting from the macroscopic approach of particle stability, the facetting of surface models, never considered in previous relaxation calculations, is introduced as a basic point in this study. Results confirm the stability of the icosahedral structure in small-size models and that of the f.c.c. structure in large-size models. In this connection the results prove that twinned f.c.c. models are more stable than f.c.c. polyhedra. They also establish the stability of the decahedral structure in a large size range, 1600 < N < 10⁵ atoms. Comparisons with macroscopic results on the stability of metal particles are presented and application to argon clusters is discussed.