Polarizability and aqueous solvation of the sulfate dianion

Polarizability of the sulfate dianion solvated in water clusters and in an extended water slab is investigated by a combination of ab initio calculations and classical and Car–Parrinello molecular dynamics. Quantum chemistry calculations at the MP2/aug-cc-pvdz level are performed for structures obtained from molecular dynamics simulations replacing water oxygens and hydrogens by fractional point charges. Sulfate polarizability in bulk water amounts to roughly 7 Å3. Despite this large value SO42− clearly prefers interior over surface solvation, in accord with previous experimental evidence for large aqueous clusters.