“…Results from several trajectories with limited numbers of particles were combined to give a globally consistent freeenergy surface describing the growth of methyl t-butyl ether (MTBE) clusters along the pathway to nucleation of a bulk liquid phase from either the vapor or aqueous solution. The analysis of equilibrium cluster statistics in small-N systems relies on the consideration of all discrete ways in which the monomers of the system can be arranged into clusters, 26 which can be mapped onto the integer partitions of N. The number of these partitions scales as (with a, b, and c being explicit constants) for partitions of bipartite integers, 28,29 which represent the combinations of clusters that can be formed from a two-component mixture of aggregants. Explicit generation of these partitions, in the latter case in particular, becomes computationally impractical even for modest N. A new approach, derived using techniques commonly used in number theory, enables the evaluation of the appropriate sums over sets of partitions without explicitly generating those partitions, resulting in a more efficient algorithm whose computational cost scales better than N 3 for single component systems and better than N 6 for bipartite mixtures.…”