Sr2+和Ba2+水分子体系结构和结合能的从头算和ABEEM/MM研究

Hydrated clusters of Sr²⁺/Ba²⁺(H₂O)n (n=1-6) were investigated by theab initiomethod and the ABEEM/MM fluctuating charge molecular force field. ABEEM/MM potential functions of cation-water interactions were constructed based on the stable structures and binding energies of the hydrated clusters were obtained. The results from ABEEM/MM are consistent with those from theab initio method. Furthermore, Sr²⁺ and Ba²⁺ aqueous solutions were studied by ABEEM/MM molecular dynamic simulations. Results show that for the Sr²⁺ aqueous solution the first and second peaks of the SrO radial distribution function (RDF) are located at 0.257and0.464nm, respectively. The coordination numbers of the water molecules for the first and second hydration shells are9.2and11.4, respectively. For the Ba2+ aqueous solution, the first and second peaks of the BaO RDF are located at 0.269 and 0.467nm, respectively. The coordination numbers of water molecules for the first and second hydration shells are 9.9 and 12.4,
respectively. These results also show good consistency with experimental observations and other theoretical simulations. Compared with the external water molecules, the water molecules in the first hydration shell are evidently polarized by the cation and their O―H bond lengths are stretched while the HOH bond anglesare found to be reduced.
[来源：中国聚合物网]