Li Xin, Yang Zhong-Zhi
Department of Chemistry, Liaoning Normal University, Dalian 116029, P. R. China.
J Phys Chem A. 2005 May 12;109(18):4102-11. doi: 10.1021/jp0458093.
We present a potential model for Li(+)-water clusters based on a combination of the atom-bond electronegativity equalization and molecular mechanics (ABEEM/MM) that is to take ABEEM charges of the cation and all atoms, bonds, and lone pairs of water molecules into the intermolecular electrostatic interaction term in molecular mechanics. The model allows point charges on cationic site and seven sites of an ABEEM-7P water molecule to fluctuate responding to the cluster geometry. The water molecules in the first sphere of Li(+) are strongly structured and there is obvious charge transfer between the cation and the water molecules; therefore, the charge constraint on the ionic cluster includes the charged constraint on the Li(+) and the first-shell water molecules and the charge neutrality constraint on each water molecule in the external hydration shells. The newly constructed potential model based on ABEEM/MM is first applied to ionic clusters and reproduces gas-phase state properties of Li(+)(H(2)O)(n) (n = 1-6 and 8) including optimized geometries, ABEEM charges, binding energies, frequencies, and so on, which are in fair agreement with those measured by available experiments and calculated by ab initio methods. Prospects and benefits introduced by this potential model are pointed out.
我们基于原子键电负性均衡与分子力学相结合的方法（ABEEM/MM）提出了一种锂离子 - 水团簇的潜在模型，该模型将阳离子以及水分子的所有原子、键和孤对电子的ABEEM电荷纳入分子力学中的分子间静电相互作用项。该模型允许阳离子位点和ABEEM - 7P水分子的七个位点上的点电荷根据团簇几何结构发生波动。锂离子第一配位层中的水分子结构强烈，阳离子与水分子之间存在明显的电荷转移；因此，离子团簇上的电荷约束包括对锂离子和第一配位层水分子的带电约束以及对外部水合层中每个水分子的电荷中性约束。基于ABEEM/MM新构建的势模型首先应用于离子团簇，并再现了Li⁺(H₂O)ₙ（n = 1 - 6和8）的气相状态性质，包括优化的几何结构、ABEEM电荷、结合能、频率等，这些结果与现有实验测量值和从头算方法计算值相当吻合。文中指出了该势模型带来的前景和益处。
