On the Nucleation Rate of Confinement-Induced Liquidlike-to-Solidlike Phase Transitions

The confinement-induced liquidlike-to-solidlike phase transition is a well-documented phenomenon observed in both experimental and computational settings. In order to better understand the kinetics and thermodynamics of this process, this study uses molecular dynamics (MD) simulations employing four different methods to examine the nucleation rate of crystalline argon from a confined liquidlike state between two solid walls. The results demonstrate that all four methods produce the same nucleation rate within a factor of two. By analyzing the mean first-passage time (MFPT) and steady-state probability distribution of the largest cluster, the free energy barrier of nucleation is also extracted, which is in the same order of magnitude as kBT. These findings quantitatively explain why confinement-induced solidification is observed in direct brutal-force MD simulations and can occur simultaneously as the confinement approaches a critical thickness. This study also provides insight into the nature of heterogeneous nucleation in nanoconfinement.