Screened Coulombic Orientational Correlations in Dilute Aqueous Electrolytes.

The ion-induced long-range orientational order between water molecules recently observed in second harmonic scattering experiments and illustrated with large scale molecular dynamics simulations is quantitatively explained using the Ornstein-Zernike integral equation approach of liquid physics. This general effect, not specific to hydrogen-bonding solvents, is controlled by electroneutrality conditions, dipolar interactions, and dielectric+ionic screening. As expected, all numerical theories recover the well-known analytical expressions established 40 years ago.