LATTICE ENERGIES OF CALCITE-STRUCTURE METAL CARBONATES - II - RESULTSFOR CACO3, CDCO3, FECO3, MGCO3, AND MNCO3

Lattice energies (Delta U) of five calcite-structure metal carbonates (i.e., CaCO3(s), CdCO3(s), FeCO3(s), MgCO3(s), and MnCO3(s)) have been calculated theoretically by separating Delta U into the following thr ee energy components: electrostatic, polarization, and repulsive. Expe rimental crystal structure data and previously determined carbonate io n charge distributions (Mandell, G. K. and Rock, P. A., Lattice energi es of calcite-structure metal carbonates I. Calculation of carbonate i on charge distributions from oxygen polarizabilities. J. Phys. Chem. S olids, 1998, 59, 695) serve as the Primary input data to the model. Th e electrostatic portion of the lattice energy (Delta U-electrostatic) is evaluated by a point charge approach, while the polarization energy contribution (Delta U-polarization) is computed via a self-consistent method, which considers both dipole/dipole and ion/dipole interaction s. Lastly, the repulsive energy segment (Delta U-repulsive) is evaluat ed by means of the Slater potential (Slater, J. C., introduction to Ch emical Physics, Ch. 13. McGraw-Hill, New York, 1939). The Delta U valu es obtained from this theoretical approach compare favorably with the corresponding experimentally based values. (C) 1998 Elsevier Science L td. All rights reserved.