Extended Modified Liquid Drop−Dynamical Nucleation Theory (EMLD−DNT) Approach to Nucleation:  A New Theory

We present a new phenomenological approach to nucleation, based on the combination of the “extended modified liquid drop” (EMLD) model and dynamical nucleation theory (DNT). The new model proposes a new cluster definition, which properly includes the effect of fluctuations, and it is consistent both thermodynamically and kinetically. The model is able to predict successfully the free energy of formation of the critical nucleus, using only macroscopic thermodynamic properties. The nucleation barrier predicted by the model vanishes at a finite value of the supersaturation, thus accounting for the spinodal, and provides excellent agreement with the results of recent simulations. Of fundamental importance is the fact that the cluster definition is based on cluster volume as well as molecular content, and that a nonarbitrary specification of volume is supplied by variational transition state theory. In this connection, the importance of allowing the “process” to define the cluster is demonstrated. This nexus between chemical dynamics and nucleation should lead to a collaboration of nucleation theorists and chemical dynamicists that will form a whole that is greater than the sum of its parts.