Hydration properties of magnesium and calcium ions from constrained first principles molecular dynamics.
J Chem Phys
; 127(7): 074503, 2007 Aug 21.
Article
en En
| MEDLINE
| ID: mdl-17718616
ABSTRACT
We studied the solvation structures of the divalent metal cations Mg(2+) and Ca(2+) in ambient water by applying a Car-Parrinello-based constrained molecular dynamics method. By employing the metal-water oxygen coordination number as a reaction coordinate, we could identify distinct aqua complexes characterized by structural variations of the first coordination shell. In particular, our estimated free-energy profile clearly shows that the global minimum for Mg(2+) is represented by a rather stable sixfold coordination in the octahedral arrangement, in agreement with experiments. Conversely, for Ca(2+) the free-energy curve shows several shallow local minima, suggesting that the hydration structure of Ca(2+) is highly variable. Implications for water exchange reactions are also discussed.
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Banco de datos:
MEDLINE
Asunto principal:
Agua
/
Calcio
/
Magnesio
Tipo de estudio:
Prognostic_studies
Idioma:
En
Año:
2007
Tipo del documento:
Article