Institute of Chemistry, State University of Campinas, UNICAMP, P.O. Box 6154, Campinas, SP 13084-862, Brazil.
J Chem Phys. 2010 Mar 21;132(11):114509. doi: 10.1063/1.3364110.
We developed a simple pair-additive Lennard-Jones plus Coulomb potential for molecular simulations of the trivalent cation Al(3+) 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(H(2)O)(6) complex. It predicts the main O-Al-O bending mode frequency to within approximately 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 Al(3+) in more complex aqueous and biomolecular systems.
我们开发了一种简单的加和型 Lennard-Jones 加上库仑势模型，用于三价阳离子 Al(3+)在水中的分子模拟，该模型能够很好地描述铝水溶液的行为。该模型预测了一个包含 6 个水分子的八面体第一层水合壳和一个平均有 12 个水分子的三角型第二层水合壳，与可用的实验确定的结构非常吻合。与 X 射线结构相比，阳离子-氧配分函数的峰位置仅略有压缩，水合焓低 10%，阳离子自扩散系数和单粒子二阶转动时间分别与非弹性中子散射和 NMR 光谱数据非常吻合。该模型还捕捉到了水合Al(H2O)6配合物的基本振动特征。它预测的主要 O-Al-O 弯曲模式频率的准确度在 5%以内，但明显高估了完全对称的 Al-O 伸缩模式的频率。总的来说，与最好的现有经典势能相比，如果不是在某些方面更好的话，所提出的模型的准确性与它们一样好，而且具有更简单的函数形式，这使得它成为更复杂的水溶液和生物分子系统中 Al(3+)计算机模拟的一种有吸引力的替代方案。
