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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >First-Principles Determination of the Absolute Hydration Free Energy of the Hydroxide Ion
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First-Principles Determination of the Absolute Hydration Free Energy of the Hydroxide Ion

机译：氢氧根离子绝对水合自由能的第一性原理测定

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摘要

The absolute hydration free energy of the hydroxide ion, ΔG_(hyd)~(298)(HO~-), a fundamental quantity in solution chemistry, has "experimental" values ranging from -90.6 to -110.0 kcal/mol. We report a first-principles determination of ΔG_(hyd)~(298)(HO~-) by using a reliable computational protocol of high-level first-principles supermolecule-continuum calculations, the same approach recently used to determine the absolute hydration free energy of the proton. In the supermolecule-continuum approach, part of the solvent surrounding the solute is treated quantum mechanically, and the remaining bulk solvent is approximately by a dielectric continuum medium accounted for by a recently developed self-consistent reaction field model known as surface and volume polarization for electrostatic interaction (SVPE) or the fully polarizable continuum model (FPCM). With this approach, the calculated results can systematically be improved by increasing the number of quantum mechanically treated solvent molecules, and ΔG_(hyd)~(298)(HO~-) is accurately predicted to be -104.5 kcal/mol. The ΔG_(hyd)~(298)(HO~-) value of -104.5 kcal/mol, combined with our previously determined ΔG_(hyd)~(298)(HO~+) value of -262.4 kcal/mol, allows the prediction of the sum of absolute hydration free energies of the proton and hydroxide to be -366.9 kcal/mol, in excellent agreement with the well-established experimental thermodynamic value of -366.6 ± 0.1 kcal/mol.
机译：氢氧根离子的绝对水合自由能ΔG_（hyd）〜（298）（HO〜-）是溶液化学中的基本量，其“实验”值范围为-90.6至-110.0 kcal / mol。我们通过使用可靠的高水平第一原理超分子-连续谱计算协议来报告ΔG_（hyd）〜（298）（HO〜-）的第一原理，该方法最近用于确定绝对无水合质子的能量。在超分子-连续谱方法中，围绕溶质的部分溶剂被量子力学处理，剩余的本体溶剂大约由介电连续介质构成，该介质由最近开发的自洽反应场模型解释，称为表面和体积极化。静电相互作用（SVPE）或完全极化的连续体模型（FPCM）。通过这种方法，可以通过增加量子机械处理的溶剂分子的数量来系统地改善计算结果，并且准确地预测ΔG_（hyd）〜（298）（HO〜-）为-104.5 kcal / mol。 -104.5 kcal / mol的ΔG_（hyd）〜（298）（HO〜-）值与我们先前确定的-262.4 kcal / mol的ΔG_（hyd）〜（298）（HO〜+）值相结合预测质子和氢氧化物的绝对水合自由能之和为-366.9 kcal / mol，与公认的实验热力学值-366.6±0.1 kcal / mol高度吻合。

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