Thermodynamic properties of small zinc clusters based on atomistic simulations

Abstract

Molecular-dynamics calculations were performed on zinc atom clusters to determine their equilibrium configurations using an embedded-atom method (EAM) potential developed for zinc. Calculation of the thermodynamic properties at different temperatures involved a Monte Carlo scheme in conjunction with statistical mechanical techniques. The harmonic approximation was used in the calculation of the vibrational contribution to the cluster partition function and the rigid-body approximation was used in the calculation of the rotational contribution. These calculations were used to examine the Helmholtz free energy of formation of the clusters as a function of cluster size, temperature and pressure with the aim of determining the nucleation rates and critical supersaturation pressures. Three cluster-growth patterns were considered in all the calculations and stability diagrams were plotted indicating the relative stability of clusters as a function of cluster size and temperature for these three growth patterns.