Stack Andrew G, Rustad James R, Casey William H
Department of Geology and Department of Chemistry, University of California, Davis, California 95616, USA.
J Phys Chem B. 2005 Dec 22;109(50):23771-5. doi: 10.1021/jp0530505.
For the first time, water exchange on a polymeric complex has been modeled using a combination of gas-phase ab initio calculations and molecular dynamics (MD) simulations. The GaO4Al12(OH)24(H2O)12(7+)aq ion (GaAl12) was chosen because high-quality experimental data exist, including an activation enthalpy (+63 +/- 7 kJ/mol) and an activation volume (+3 +/- 1 cm3/mol). We took a two-step approach. First, the local solvent structure and the initial states for reaction were inferred from the molecular dynamics simulations. Second, we used this information to evaluate initial-state structures in the ab initio calculations. The energy differences between the initial and transition states from the ab initio calculations varied from +59 kJ/mol to +53 kJ/mol depending upon details, closely approximating the activation enthalpy.
首次使用气相从头算计算和分子动力学（MD）模拟相结合的方法对聚合物配合物上的水交换进行了建模。选择GaO4Al12(OH)24(H2O)12(7+)aq离子（GaAl12）是因为存在高质量的实验数据，包括活化焓（+63 +/- 7 kJ/mol）和活化体积（+3 +/- 1 cm3/mol）。我们采用了两步法。首先，从分子动力学模拟推断局部溶剂结构和反应的初始状态。其次，我们利用这些信息在从头算计算中评估初始状态结构。从头算计算得出的初始态和过渡态之间的能量差根据细节从+59 kJ/mol到+53 kJ/mol不等，与活化焓非常接近。
