Chloride anion on aqueous clusters, at the air-water interface, and in liquid water:: Solvent effects on Cl- polarizability

The effect of asymmetric aqueous solvation on the polarizability of the chloride anion is investigated by accurate ab initio calculations on structures obtained from classical molecular dynamics and Car-Parrinello molecular dynamics simulations. It is shown that a water environment significantly reduces the halide polarizability on clusters, at interfaces, and in the bulk. In the relatively rigid cluster environment, the amount of this reduction strongly depends on the particular geometry of the complex, while in more disordered, extended liquid systems, the geometric effect is much weaker. Therefore, a single effective value around 4 Angstrom3 may be employed for the chloride anion polarizability in aqueous environments.