A Method for Analyzing the Non-Stationary Nucleation and Overall Transition Kinetics. A Case of Water

We present the statistical method as a direct extension of the mean first-passage time concept to the analysis of molecular dynamics simulation data of a phase transformation. According to the method, the mean first-passage time trajectories for the first $(i=1)$ as well as for the subsequent ($i=2$, $3$, $4$, $\ldots$) nucleation events should be extracted, that allows one to calculate the time-dependent nucleation rate, the critical value of the order parameter (the critical size), the waiting times for the nucleation events and the growth law of the nuclei -- i.e. all the terms, which are usually necessary to characterize the overall transition kinetics. There are no restrictions in the application of the method by the specific thermodynamic regions; and the nucleation rate parameters are extracted according to their basic definitions. The method differs from the Wedekind-Bartell scheme and its modification [A.V. Mokshin, B.N. Galimzyanov, J. Phys. Chem. B {\bf 116}, 11959 (2012)], where the passage-times for the first (largest) nucleus are evaluated only and where the average waiting time for the first nucleation event is accessible instead of the true steady-state nucleation time scale. We demonstrate an efficiency of the method by its application to the analysis of the vapor-to-liquid transition kinetics in water at the different temperatures. The nucleation rate/time characteristics and the droplet growth parameters are computed on the basis of the coarse-grained molecular dynamics simulation data.

Anatolii V. Mokshin, Bulat N. Galimzyanov · 2013