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THE CRYSTALLIZATION OF ALKALI-HALIDES FROM AQUEOUS-SOLUTION - AN APPLICATION OF DENSITY-FUNCTIONAL THEORY

TitleTHE CRYSTALLIZATION OF ALKALI-HALIDES FROM AQUEOUS-SOLUTION - AN APPLICATION OF DENSITY-FUNCTIONAL THEORY
Publication TypeJournal Article
Year of Publication1991
AuthorsUrsenbach, CP, Patey, GN
JournalJournal of Chemical Physics
Volume95
Pagination485-493
Date PublishedJul
Type of ArticleArticle
ISBN Number0021-9606
KeywordsAPPROXIMATION, INVARIANT EXPANSION, MEAN SPHERICAL MODEL, ORNSTEIN-ZERNIKE EQUATION, SIMULATION, SPHERES, TRANSITION, WATER
Abstract

Density-functional theory is applied to the problem of salt crystallization from solution and explicit results are given for model aqueous alkali-halide systems. Both direct- and Fourier-space methods of calculation are considered and it is found that only the direct (i.e., r space) method converges sufficiently rapidly to provide reliable results for ionic crystals at 25-degrees-C. It is shown that the density-functional method is capable of predicting crystallization, but that the solid-state parameters and, for some salts, the crystal structures obtained are in poor agreement with experiment or computer simulations. The calculated crystal/solution coexistence concentrations are found to be extremely sensitive to the short-range part of the interionic pair potentials. This is consistent with earlier observations that the activity coefficients of model aqueous alkali-halide solutions are very strongly dependent upon the short-range ion-ion interactions. Therefore, we do not believe that this sensitivity to details of the short-range interionic potentials is an artifact of theoretical approximations, but rather a real effect significantly influencing crystallization.

URL<Go to ISI>://A1991FT84700048