Comparison of cluster definitions in homogeneous nucleation rate calculations

We compare cluster definitions used in the framework of classical nucleatio n theory to estimate nucleation rates. Cluster definitions influence the ma gnitude of the partition functions used to calculate the equilibrium consta nts that relate aggregation and fission rate constants. Therefore, cluster definitions affect calculated nucleation rates. Geometric and energetic def initions are simple to apply but are prone to systematic errors. We recomme nd the dynamic cluster definition as the most likely to lead to calculated rates agreeing with measurements. The definitions are illustrated using a s imple xenon model.