Wang, YT (reprint author), Chinese Acad Sci, Inst Theoret Phys, State Key Lab Theoret Phys, Beijing 100190, Peoples R China.
The behavior of saturated aqueous NaCl solutions under a constant external electric field (E) was studied by molecular dynamics (MD) simulation. Our dynamic MD simulations indicated that the irreversible nucleation process towards crystallization is accelerated by a moderate E but retarded or even prohibited under a stronger E, which can be understood by the competition between self-diffusion and drift motion. The former increases with E, thereby accelerating the nucleation process, whereas the latter pulls oppositely charged ions apart under a stronger E, thereby decelerating nucleation. Additionally, our steady-state MD simulations indicated that a first-order phase transition occurs in saturated solutions at a certain threshold E-c. The magnitude of E-c increases with concentration because larger clusters form more easily when the solution is more concentrated and require a stronger E to dissociate.