First-Principles Ion-Water Interaction Potentials for Highly Charged Monatomic Cations. Computer Simulations of Al3+, Mg2+, and Be2+ in Water

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• 作者：José ; M. Martí ; nez ; Rafael R. Pappalardo ; and Enrique Sá ; nchez Marcos
• 刊名：Journal of the American Chemical Society
• 出版年：1999
• 出版时间：April 7, 1999
• 年：1999
• 卷：121
• 期：13
• 页码：3175 - 3184
• 全文大小：151K
• 年卷期：v.121,no.13(April 7, 1999)
• ISSN：1520-5126

文摘

The concept of hydrated ion [M(H<SUB>2O)_m ]ⁿ⁺ has been used to describe interactions of highly chargedmonatomic cations in water. Ab initio interaction potentials for Al³⁺, Mg²⁺, and Be²⁺ have been developed onthe basis of that previously applied to the Cr³⁺ hydration study (Martínez et al. J. Chem. Phys. 1998, 109,1445). Transferability of the different contributions to the intermolecular potentials that describe the interactionsbetween the central cation and the first hydration shell, Mⁿ⁺-(H₂O)_I, and the hydrate with bulk water molecules,[M(H₂O)_m ]ⁿ⁺-(H₂O)_bulk, have been examined. Results indicate that a reduced number of points (~40 quantumchemical computations) are enough to get the basic and differential features of each cation. MD simulations(200 ps) for the hydrate of each cation plus 512 TIP4P H₂O have been performed. Structural properties suchas RDFs among different pairs of atoms in the system and orientational parameter are presented. Likewise,dynamical properties such as self-diffusion coefficients, reorientational and mean residence times, and powerspectra have been obtained and analyzed. The comparative study of the properties derived from the hydrationof each cation and the degree of transferability of the intermolecular potentials based on their main featuresis thoroughly discussed. Prospectives and benefits introduced by this type of flexible hydrated ion-waterinteraction potential in molecular simulations are pointed out.