The Aqueous Ca2+ System,in Comparison with Zn2+, Fe3 +, and Al3 +: An Ab Initio Molecular Dynamics Study |
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| Authors: | Dr Stuart Bogatko Dr Emilie Cauët Dr Eric Bylaska Dr Gregory Schenter Dr John Fulton Prof John Weare |
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| Institution: | 1. Chemistry and Biochemistry Department, University of California, San Diego, 9500 Gilman Dr., La Jolla, CA 92093 (USA);2. Current address: Eenheid Algemene Chemie, Vrije Universiteit Brussel (VUB), Faculteit Wetenschappen, Pleinlaan 2, 1050 Brussels (Belgium);3. Current address: Service de Chimie Quantique et Photophysique, Université Libre de Bruxelles, CP 160/09, 50 Avenue F. D. Roosevelt, 1050 Brussels (Belgium);4. Pacific Northwest National Laboratory, Richland, WA (USA) |
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| Abstract: | Herein, we report on the structure and dynamics of the aqueous Ca2+ system studied by using ab initio molecular dynamics (AIMD) simulations. Our detailed study revealed the formation of well‐formed hydration shells with characteristics that were significantly different to those of bulk water. To facilitate a robust comparison with state‐of‐the‐art X‐ray absorption fine structure (XAFS) data, we employ a 1st principles MD‐XAFS procedure and directly compare simulated and experimental XAFS spectra. A comparison of the data for the aqueous Ca2+ system with those of the recently reported Zn2+, Fe3+, and Al3+ species showed that many of their structural characteristics correlated well with charge density on the cation. Some very important exceptions were found, which indicated a strong sensitivity of the solvent structure towards the cation′s valence electronic structure. Average dipole moments for the 2nd shell of all cations were suppressed relative to bulk water. |
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| Keywords: | ab initio calculations calcium cations solvent effects water chemistry XAFS |
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