On the direct evaluation of the equilibrium distribution of clusters by simulation

An expression is derived that relates the average population of a particular type of cluster in a metastable vapor phase of volume V tot to the probability, estimated by simulation, of finding this cluster in a system of volume V taken inside V tot , where V!V tot . Correct treatment of the translational free energy of the cluster is crucial for this purpose. We show that the problem reduces to one of devising the proper boundary condition for the simulation. We then verify the result obtained previously for a low vapor density limit @J. Chem. Phys. 108, 3416 ~1998!#. The difficulty implicit in our recent calculation @J. Chem. Phys. 110, 5249 ~1999!#, in which the approach in the former was generalized to higher vapor densities, is shown to be resolved by a method already suggested in that paper. © 1999 American Institute of Physics. @S0021-9606~99!50944-6#