Sposito 9505629 Simulation methodologies developed recently by the Principal Investigator and his coworkers will be applied to perform Monte Carlo (MC) and molecular dynamics (MD) calculations of molecular configurations at the interface between 2:1 clay minerals and aqueous solution. Quantum chemical calculations of clay mineral molecular structure also will be performed to examine the accuracy of the potential functions used in the simulations. The project objectives are: (1) to perform and evaluate MC and MD simulations of hydrated Li+, Na+, K+, Cs2+, and Mg2+-saturated 2:1 clay minerals to deduce the configurations, mobilities, and reactivities of adsorbed water molecules and counter-ions; (2) to perform ab initio quantum chemical calculations of the counter -ion-clay mineral potential energy surface for monovalent and bivalent cation-saturated 2:1 clay minerals to improve the accuracy of the MC/MD simulations. The results will be compared with a variety of experimental data, and will provide general comparative insights as to the structure of the interface between 2:1 clay minerals and aqueous solutions that are relevant to low-temperature geochemical weathering processes.
