Argon clusters nucleation rate

Hruby, J., Viisanen, Y., and Strey, R. (1996) Homogeneous nucleation rates for n-pentanol in argon determination of the critical cluster size, J. Chem. Phys. 104, 5181-5187. 

These studies seem to indicate that, for structureless particles, it is most important to understand the dependence of nucleation rate coefficients on cluster size for very small clusters. At the low temperatures appropriate for argon nucleation, the decay rate coefficient for excited clusters for clusters larger than seven or eight monomers becomes essentially zero, and the capture cross section for this size cluster apparently increases very slowly with n. These facts should make it very easy to compute steady-state nucleation rates for argon, provided similar information is available for the rate coefficients for the "quenching" reactions of equation (2), since it may not be necessary to use trajectories to calculate any of these rate coefficients for clusters larger than ten or twelve monomers in size. 

For these theories, the present work provides a numerical calibra-tion for the argon model by yielding values for constants that must otherwise be treated as arbitrary parameters and by determining how closely the theoretical predictions are followed by the model system. The well behaved dependence of the decay rates and capture cross sections upon cluster size indicates that it may not be necessary to perform such calculations for larger clusters. A direct extension of the present type of study could supply all of the rate coefficients necessary to reformulate the steady-state nucleation rate in terms of quantities which could be either directly calculated or approximated with reasonable accuracy by use of the theoretical models. 

Mandell, McTague, and Rahman used molecular dynamics to study crystal nucleation in a three-dimensional Lennard-Jones system representing supercooled liquid argon. These workers have observed the formation of solid clusters at a rate which they believe is consistent with classical nucleation theory, and a similar calculation for liquid rubidium also produced crystal nucleation. 

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