Abstract
We explore the deconvolution of correlations for the interpretation of microstructural behavior of aqueous electrolytes according to the NDIS approach toward the experimental determination of ion coordination numbers of systems involving oxyanions, in particular, sulfate anions. We discussed the gist underlying the alluded interplay in the title of this presentation, and emphasized the expectations, and highlight the significance of tackling the challenging NDIS experiments. Specifically, we focused on the potential occurrence of Ni+2···SO4–2 pair formation with both anion interaction sites, identified its signature in the neutron-weighted distribution functions, suggested novel ways for either the direct probe of the strength for the subsequent correction of its effects on the experimentally measured coordination numbers, or the determination of anion coordination numbers free of contributions through the implementation of null-cation environments. For that purpose we performed isochoric–isothermal simulations of 1.72m NiSO4 aqueous solutions at ambient conditions to generate the relevant radial distribution functions required in the analysis (a) to identify the individual partial contributions to the total neutron-weighted distribution function, (b) to isolate and assess the contribution of Ni+2···SO4–2 pair formation, (c) to test the accuracy of the neutron diffraction with isotope substitution based coordination calculations and X-ray diffraction based assumptions, and (d) to describe the water coordination around both the sulfur and oxygen sites of the sulfate ion. We finally discussed the strength of this interplay on the basis of the inherent molecular simulation ability to provide all pair correlation functions that fully characterize the system microstructure and allows us to “reconstruct” the eventual NDIS output, i.e., to take an atomistic “peek” at the local environment around the isotopically-labeled species before any experiment is ever attempted, and ultimately, to test the accuracy of the “measured” NDIS-based coordination numbers against the actual values by the “direct” counting.