Ab Initio Study on Molecular and Thermodynamic Properties of Water: A Theoretical Prediction of pKw over a Wide Range of Temperature and Density
Ab Initio Study on Molecular and Thermodynamic Properties of Water: A Theoretical Prediction of pKw over a Wide Range of Temperature and Density
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水分子和热力学性质的从头算研究：大范围温度和密度下 pKw 的理论预测
DOI：
10.1021/jp9911806
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发表时间：
1999
影响因子：
3.3
通讯作者：
F. Hirata
中科院分区：
文献类型：
--
作者：
Hirofumi Sato;F. Hirata
水的离子积（pKw）已经在宽的温度（0 - 600 °C）和密度（0.6 - 1.4 g/cm 3）范围内通过从头算电子结构理论结合分子液体统计力学中的扩展参考相互作用位点模型（RISM-SCF/MCSCF）进行了计算。我们考虑的自电离过程（H2O + H2O <$H3O + + OH-），把H2O，H3 O+，和OH-作为“溶质”分子在水溶液中，并评估分子的几何形状，电子结构，溶剂化结构，和这些物种的自由能分量的功能的化学条件。从理论上得到的pKw的结果表明，在所研究的所有温度下，pKw随密度的增加而单调减小，与实验观察符合良好雅阁。该行为基本上由与反应相关的溶剂化自由能的差异Δμ（H3 O+）+ Δμ（OH-）− 2Δμ（H2O）决定。Δμ（OH-）表现出与密度的依赖关系，这与实验结果完全不同。
The ionic product of water (pKw) has been calculated in a wide range of temperature (0−600 °C) and density (0.6−1.4 g/cm3) by means of ab initio electronic structure theory combined with the extended reference interaction site model in statistical mechanics for molecular liquids (RISM-SCF/MCSCF). We consider the autoionization process (H2O + H2O ⇌ H3O+ + OH-) by regarding H2O, H3O+, and OH- as “solute” molecules in an aqueous solution and evaluate molecular geometries, electronic structure, solvation structure, and free energy components of these species as functions of thermodynamical conditions. The results for pKw obtained from the theory have shown a monotonical decrease with increasing density at all the temperatures investigated, in good accord with the experimental observation. The behavior is determined essentially by the difference in solvation free energies, Δμ(H3O+) + Δμ(OH-) − 2Δμ(H2O), associated with the reaction. The Δμ(OH-) shows the density dependence, which is entirely different from tha...