Building models for the initial stages of nucleation: CaCO3 revisited

Building quantitative models of nucleation remains a challenge in both simulation and theory.
A more difficult task is to provide the quantitative molecular information that is needed to describe both the structure of the relevant clusters and thermodynamics that precedes nucleation.
Herein, we present a molecular model of nucleation based on the details of ion-pairing under dilute solution conditions. With this assumption, we can construct a coarse-grained representation
that allows for the determination of converged cluster populations and a concomitant solution model that can be directly compared with xray
absorption and titration measurements. The conclusions based on this model is that the nucleation of CaCO3 proceeds classically with the dominant solution species being single ions and their pairs.
Moreover, there is no need to use concepts such as pre-nucleation clusters to explain the pathways that precede nucleation for CaCO3.

This work was supported by the U.S. Department of Energy (DOE), Office of Science, Office of Basic Energy Sciences.