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The Aqueous Ca 2+ System, in Comparison with Zn 2+ , Fe 3 + , and Al 3 + : An Ab Initio Molecular Dynamics Study
Author(s) -
Bogatko Stuart,
Cauët Emilie,
Bylaska Eric,
Schenter Gregory,
Fulton John,
Weare John
Publication year - 2013
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201202821
Subject(s) - x ray absorption fine structure , aqueous solution , valence (chemistry) , chemistry , ab initio , molecular dynamics , electronic structure , ab initio quantum chemistry methods , atom (system on chip) , analytical chemistry (journal) , density functional theory , crystallography , computational chemistry , molecule , spectroscopy , physics , organic chemistry , chromatography , computer science , embedded system , quantum mechanics
Herein, we report on the structure and dynamics of the aqueous Ca 2+ 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 Ca 2+ system with those of the recently reported Zn 2+ , Fe 3+ , and Al 3+ 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.