Abstract:

Molecular d namics studies are reported for LaCI, solutions at two different concentrations and temperatures, and for isolated aqueous Lay+ ions. Ion-water clusters La(H,O):+ with n = 61 and n = 100 and systems consisting of one ion and 100 or 200 water molecules in the usual periodic box, as well as solutions of 7 (4) cations and 21 (12) anions in 190 (200) water molecules, corresponding to 2 and 1 . I m solutions, respectively, were investigated. The 2 m solution was investigated at two different temperatures. The results for the static structure, with special emphasis on the hydration structure of the La3+ ion, are discussed in terms of radial distribution functions and resulting hydration numbers, and various other correlations. A concentration-dependent hydration number is obtained here for the La3+ ion, decreasing from 12 at infinite dilution to 10.2 at 2 m concentration. These results are compared with X-ray data and discussed in light of the hydration numbers observed for aqueous ions in general.