On the reduced moment in the transient regime of homogeneous nucleation

One of the parameters characterizing the evolution of nucleation in the transient regime is the so-called reduced moment, a dimensionless quantity. This parameter describes the steepness with which the nucleation rate approaches its steady state. Until recently, very little had been known about this parameter in real systems, although a widely quoted 1969 theory [D. Kashchiev, Surf. Sci. 14, 209 (1969)] existed that formally described nucleation in the transient regime. This theory has been shown to be incorrect in its implication about the reduced moment. Molecular dynamics simulations have recently greatly clarified what happens in the transient regime. It turns out that the reduced moment depends strongly on the size of the nucleus under consideration, and, for a rapidly quenched liquid, it substantially exceeds unity for small nuclei but approaches unity as nuclei increases in size. The objective of this paper is to illustrate the behavior of the reduced moment and to show how this behavior is a natural consequence of the kinetics of the nucleation process.