Department of Chemistry and Biochemistry, University of North Carolina, Wilmington, North Carolina 28403, USA.
J Phys Chem A. 2009 Mar 12;113(10):2144-51. doi: 10.1021/jp809236c.
Ab initio molecular dynamics is used to investigate the propensity of the hydronium ion for the interface of an HCl solution containing 1 HCl and 96 water molecules in a slab geometry. Unconstrained trajectories in the NVT and NVE ensemble reveal a clear preference of the hydronium ion for the interfacial region and several qualitative spectral features of interfacial hydronium ions. Orientational distribution functions indicate that the C(3) axis of the hydronium is tilted with respect to the surface normal, thereby allowing surface proton transfer reactions to occur. Finally, constrained simulations combined with thermodynamic integration are used to compute the potential of mean force for the transfer of the hydronium from the bulk to the interface and into the gas phase as a pure H(3)O(+). The potential of mean force is found to exhibit a shallow free energy minimum of roughly 1.3 kcal/mol with respect to the bulk, in good agreement with very recent calculations based on polarizable force fields and empirical valence bond potentials.
从头算分子动力学用于研究在含有 1 个 HCl 和 96 个水分子的 HCl 溶液的平板几何形状的界面处，氢离子的界面倾向。在 NVT 和 NVE 系综中不受约束的轨迹揭示了氢离子对界面区域的明显偏好，以及界面氢离子的几个定性光谱特征。取向分布函数表明，氢离子的 C(3)轴相对于表面法线倾斜，从而允许表面质子转移反应发生。最后，使用约束模拟结合热力学积分来计算氢离子从本体到界面再到气相作为纯 H(3)O(+)的转移的平均力势能。发现平均力势能相对于本体表现出一个浅的自由能最小值，约为 1.3 kcal/mol，与基于极化力场和经验价键势的最近计算结果非常吻合。
