The structure of CaCl2 aqueous solutions over a wide range of concentration.: Interpretation of diffraction experiments via molecular simulation

A detailed analysis of the water structure around the ionic species in aqueous CaCl2 solutions is performed by molecular dynamics over a wide range of concentration (0<mless than or equal to9.26) at ambient conditions. The goals behind the study are to address a long-standing controversy regarding the actual coordination number of aqueous Ca+2, to characterize the hydration structure of Ca+2, and consequently to interpret the origin of the disparity in the reported experimental data, to describe the additional information available from simulation to augment the first-order difference method in the determination of the species coordination numbers from neutron diffraction with isotopic substitution (NDIS) experiments, and to attain additional insights into the distribution of the "tilting" and "wagging" ion-water angles and their relation with the conventional configurational definitions. (C) 2003 American Institute of Physics.