A Lennard-Jones plus Coulomb potential for Al3+ ions in aqueous solutions

作者：Faro Tatiana M C; Thim Gilmar P; Skaf Munir S^*

来源：Journal of Chemical Physics, 2010, 132(11): 114509.

DOI：10.1063/1.3364110

• aluminium
• enthalpy
• Lennard-Jones potential
• liquid structure
• molecular dynamics method
• positive ions
• potential energy functions
• self-diffusion
• solvation
• vibrational modes

We developed a simple pair-additive Lennard-Jones plus Coulomb potential for molecular simulations of the trivalent cation Al3+ in water which accounts reasonably well for the behavior of aluminum aqueous solutions. The model predicts an octahedral first hydration shell containing 6 water molecules and a trigonal second shell with 12 molecules on average, in good agreement with the available experimentally determined structure. The peak positions of the cation-oxygen radial distribution function are only slightly compressed compared to the x-ray structure, the hydration enthalpy is 10% too low, and the cation self-diffusion coefficient and the single-particle second rank reorientational time are in excellent agreement with inelastic neutron scattering and NMR spectroscopy data, respectively. The model also captures the essential vibrational features of the hydrated [Al(H2O)(6)](3+) complex. It predicts the main O-Al-O bending mode frequency to within similar to 5%, but significantly overestimates the frequency of the totally symmetric Al-O stretching mode. Overall, the accuracy of the proposed model is as good as the best available classical potentials, if not better in some aspects, with a much simpler functional form, which makes it an attractive alternative for computer simulations of Al3+ in more complex aqueous and biomolecular systems.

• 出版日期2010-3-21