Ab initio molecular dynamics study of a highly concentrated LiCl aqueous solution

被引:75
作者
Petit, L. [1 ]
Vuilleumier, R. [2 ]
Maldivi, P. [1 ]
Adamo, C. [3 ]
机构
[1] CEA UJF, INAC LCIB, Lab Reconnaissance Ion & Chim Coordinat, UMRE 3, F-38054 Grenoble 9, France
[2] Univ Paris 06, Lab Phys Theor Mat Condensee, UMR7600, F-75252 Paris 05, France
[3] Ecole Natl Super Chim Paris, Lab Electrochim & Chim Anal, CNRS, UMR 7575, F-75231 Paris 05, France
关键词
D O I
10.1021/ct800007v
中图分类号
O64 [物理化学(理论化学)、化学物理学];
学科分类号
070304 ; 081704 ;
摘要
The properties of a highly concentrated aqueous lithium chloride solution (vertical bar LiCl vertical bar = 14 mol L-1) are investigated using Car-Parrinello molecular dynamics. The coordination spheres of lithium ions, chloride ions, and water molecules are described successively. On the whole, our simulation provides results-distances and coordination numbers-in very good agreement with experimental data. The lithium solvation shell is found to exhibit a tetrahedral configuration on average, with three stable clusters observed during the simulation: Li+-4H(2)O, Li+(H2O)(3)Cl-, and Li+(H2O)(2)(Cl-)(2). The chloride coordination sphere is logically formed by strong Cl-H hydrogen bonds with neighboring water molecules, for a mean coordination number of 4.4. The structuring of water molecules is strongly affected by the high concentration in LiCl. The hydrogen bond network is globally broken down, but little variation is calculated on water dipoles (mu = 3.07 D) because of the strong polarization from Li+ and CI- ions. We also point out some of the characteristic features of such a highly concentrated solution: water bridging between Li+ and CI- hydration spheres, Li+-Cl- ion-pairing, and intermediate behavior between dilute solutions and molten salts. Finally, the reliability of our simulation to describe ion-pairing is discussed.
引用
收藏
页码:1040 / 1048
页数:9
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