A molecular theory of the homogeneous nucleation rate. II. Application to argon vapor

The molecular theory of the homogeneous nucleation rate based on the n/v-St illinger cluster, and developed in the preceding paper (paper I), is applie d to the condensation of supersaturated argon vapor, in a preliminary calcu lation of the rate of nucleation for a single set of conditions (temperatur e=85 K, pressure=2500 Torr). Free energies are obtained by means of Monte C arlo simulation. Upper and lower bounds differing by only two orders of mag nitude are obtained. Since the best current measurements of vapor phase nuc leation rates are accurate to within about a single order of magnitude, thi s result is considered promising. The direction of future work to improve t he accuracy of the predicted rate is clear, and considerable improvement sh ould be possible. These directions are discussed in the paper. Also, the es sentially non ad hoc nature of the n/v-Stillinger cluster is demonstrated b y the appearance of a range of connectivity distances (in a predicted locat ion) within which the calculated nucleation rate is insensitive to the conn ectivity distance. As in the case of paper I, subtle features of the nuclea tion process, unnoticed in earlier theories, are revealed. (C) 1999 America n Institute of Physics. [S0021-9606(99)50313-9].