LIGHT-METAL IONS IN WATER - QUANTAL AND CLASSICAL SIMULATIONS FOR LI7+

Path integral Monte Carlo computations have been done to study the loc al structure of water molecules around an isolated lithium ion (Li-7()) at T=298K. The solute was treated as a quantal particle and the wat er solvent was treated classically. The water-water interaction was mo delled by the MCY pair-potential and the solute-water interaction by t he Kistenmacher et al. pair-potential. Purely classical simulations, a t the same conditions and using the same model potentials, where also performed for comparison. Significant changes are observed on the resu lts of the quantal simulations when compared with the results of the c lassical simulation. The major difference is the coordination number t hat increases from 5, the result of the classical simulation, to 6, fo r the quantal simulation. In addition, structural analysis of the gene rated configurations showed that the local structure of the water mole cules surrounding the ion is also clearly different in the two simulat ions. The reliability of the results is discussed.