Madelung Parameters and Electrostatic Energies for Calcite, Aragonite, and Vaterite and the Charge Distribution on the Carbonate Ion

The electrostatic energy changes and Madelung parameters for the process $${\mathrm{CaCo}}_3(\mathrm{c}\mathrm{)\to }{\mathrm{Ca}}^{\text{2+}}(\mathrm{g}\mathrm{)+}{\mathrm{CO}}_3^{\text{2−}}(\mathrm{g})$$ have been computed assigning various distributed charges to the ${\mathrm{CO}}_3^{\text{2‐}}$ ion for the calcite, aragonite, and vaterite forms of calcium carbonate. The results are expressed as quadratic one‐parameter functions, $\mathrm{A+BQ(}\mathrm{O}\mathrm{)+CQ(}\mathrm{O}{)}^2$ , of the charge Q(O) placed on the oxygen atom of the ${\mathrm{CO}}_3^{\text{2‐}}$ ion. A comparison with previous calculations is made and the charge distribution and quadrupole moment of the CO₃^2‐ ion estimated.