Bonthuis Douwe Jan, Mamatkulov Shavkat I, Netz Roland R
Rudolf Peierls Centre for Theoretical Physics, University of Oxford, Oxford OX1 3NP, United Kingdom.
Ion-Plasma and Laser Technologies Institute of the Uzbekistan AS, Tashkent, Uzbekistan.
J Chem Phys. 2016 Mar 14;144(10):104503. doi: 10.1063/1.4942771.
We optimize force fields for H3O(+) and OH(-) that reproduce the experimental solvation free energies and the activities of H3O(+) Cl(-) and Na(+) OH(-) solutions up to concentrations of 1.5 mol/l. The force fields are optimized with respect to the partial charge on the hydrogen atoms and the Lennard-Jones parameters of the oxygen atoms. Remarkably, the partial charge on the hydrogen atom of the optimized H3O(+) force field is 0.8 ± 0.1|e|--significantly higher than the value typically used for nonpolarizable water models and H3O(+) force fields. In contrast, the optimal partial charge on the hydrogen atom of OH(-) turns out to be zero. Standard combination rules can be used for H3O(+) Cl(-) solutions, while for Na(+) OH(-) solutions, we need to significantly increase the effective anion-cation Lennard-Jones radius. While highlighting the importance of intramolecular electrostatics, our results show that it is possible to generate thermodynamically consistent force fields without using atomic polarizability.
我们优化了H₃O⁺和OH⁻的力场，使其能够重现实验溶剂化自由能以及浓度高达1.5 mol/l的H₃O⁺Cl⁻和Na⁺OH⁻溶液的活度。力场针对氢原子上的部分电荷以及氧原子的 Lennard-Jones 参数进行了优化。值得注意的是，优化后的H₃O⁺力场中氢原子的部分电荷为0.8±0.1|e|，显著高于非极化水模型和H₃O⁺力场通常使用的值。相比之下，OH⁻氢原子的最佳部分电荷结果为零。标准组合规则可用于H₃O⁺Cl⁻溶液，而对于Na⁺OH⁻溶液，我们需要显著增加有效的阴离子 - 阳离子Lennard-Jones半径。在强调分子内静电作用重要性的同时，我们的结果表明，无需使用原子极化率就有可能生成热力学上一致的力场。
