Ab Initio molecular dynamics study of carbon dioxide and bicarbonate hydration and the nucleophilic attack of hydroxide on CO2
Ab Initio molecular dynamics study of carbon dioxide and bicarbonate hydration and the nucleophilic attack of hydroxide on CO2
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DOI：
10.1021/jp068475l
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发表时间：
2007-05-03
影响因子：
3.3
通讯作者：
Kurtz, Ira
中科院分区：
文献类型：
--
作者：
Leung, Kevin;Nielsen, Ida M. B.;Kurtz, Ira
我们应用从头算分子动力学（AIMD）来研究液态水中二氧化碳分子以及碳酸氢根和碳酸根阴离子的水合结构。我们还计算了与氢氧根离子对二氧化碳的亲核攻击相关的自由能变化。 CO2 的行为类似于疏水性物质，与水分子的相互作用较弱。碳酸氢根和碳酸根离子具有很强的水合性，分别与平均 6.9 和 8.7 个水分子配位。使用密度泛函理论和二阶 Moller-Plesset 微扰理论 (MP2) 结合高质量基组研究气相反应的能量学。使用伞式采样技术，在用 MP2 结果校正 AIMD 能量后，计算与 CO2 + OH- -> HCO3- 反应相关的标准态水相自由能差。我们的预测与实验非常吻合。进一步分析了沿反应坐标的水合结构，该结构产生了预测的 9.7 kcal/mol 标准态自由能垒。
We apply ab initio molecular dynamics (AIMD) to study the hydration structures of the carbon dioxide molecule and the bicarbonate and carbonate anions in liquid water. We also compute the free energy change associated with the nucleophilic attack of the hydroxide ion on carbon dioxide. CO2 behaves like a hydrophobic species and exhibits weak interactions with water molecules. The bicarbonate and carbonate ions are strongly hydrated and coordinate to an average of 6.9 and 8.7 water molecules, respectively. The energetics for the reaction in the gas phase are investigated using density functional theory and second-order Moller-Plesset perturbation theory (MP2) in conjunction with high-quality basis sets. Using umbrella sampling techniques, we compute the standard state, aqueous phase free energy difference associated with the reaction CO2 + OH- -> HCO3- after correcting AIMD energies with MP2 results. Our predictions are in good agreement with experiments. The hydration structures along the reaction coordinate, which give rise to a predicted 9.7 kcal/mol standard state free energy barrier, are further analyzed.