Molecular-dynamics simulation of molten alkali carbonates

Molecular-dynamics simulations are performed on molten Li2CO3, Na2CO3, and K2CO3 in the N, V, T ensemble at 1200 K. The pair potentials contain only Coulomb interaction and Born-type repulsion, with a parametrization based upon ab initio interaction energies, from which electronic polarization effects have been subtracted. It is shown that, even at this level, a significant change in structure of the melt is observed on going from Li2CO3 to K2CO3. The self-diffusion constants of the ions are reproduced fairly well by the calculations. It is found that rotation of the CO2- 3 ions is substantially easier in K2CO3 than in Li2CO3.