Determining the Complete Stability of Calcite Kink Sites: Real vs Ideal

03 May 2023, Version 1
This content is a preprint and has not undergone peer review at the time of posting.


Kink sites play a pivotal role in the growth and dissolution of materials at the solid-liquid interface. Despite this, little is known about the thermodynamic stability of such sites. Calcium carbonate, in the form of calcite, is one of the most abundant biominerals and a natural means of carbon sequestration in the environment. Here we present a complete determination of the standard free energies for all 16 individual kink sites for the significant case of the calcite (10-14)--water interface using both alchemical and pathway-based simulation techniques. The results reveal the importance of distinguishing between real and ideal ion-binding free energies at surfaces, especially for calcite-water where the interfacial potential can alter values by more than 100 kJ/mol per site. Individual kink site stabilities are found to show variations in excess of 60 kJ/mol, which can help explain observed differences in growth rates between the two distinct steps of calcite.


molecular dynamics
crystal growth
free energy calculations
interfacial potential

Supplementary materials

Supporting information
Contains, alternative view of calcite surface structure, methods for LAMMPS simulations, free energy surfaces for restrained ion removal from kink sites at the calcite (10-14)-water interface, components of the standard free energies for the alchemical cycle computed with OpenMM, ideal kink site stabilities computed using LAMMPS, ion pair stabilities at kink sites, and the interfacial potential at the halite (NaCl) (001)-water interface.


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