Utility of chemical computations in predicting solution free energies of metal ions
Utility of chemical computations in predicting solution free energies of metal ions
复制标题
DOI：
10.1080/08927022.2017.1342127
复制
发表时间：
2018-01-01
影响因子：
2.1
通讯作者：
Rempe, Susan B.
中科院分区：
文献类型：
--
作者：
Chaudhari, Mangesh I.;Pratt, Lawrence R.;Rempe, Susan B.
本文研究了二价碱土金属离子自由能的准化学理论（Ba、Sr、Ca、Mg）的水溶液中的离子，强调：（a）金属离子和邻近的水分子之间的相互作用与传统的化学效应一样强;（B）QCT直接建立在可获得的电子结构计算上，但依赖于充分阐述的分子统计热力学;（c）QCT为确定分析用协调编号提供了便利选择。我们调查利用直接QCT与内壳空调，替代传统的空调动机的广义范德华观点。另一种方法效果很好：VanderWaals排斥相互作用的非高斯效应并不严重，并且替代条件改善了QCT计算的便利性。从头算和力场分子动力学（AIMD和FFMD）与标准模型之间的比较表明，FFMD可能夸大了内壳层离子水簇热运动的非谐性。与一般令人鼓舞的支持调和近似隐含的条件，观察有助于解释显着的成功的集群为基础的QCT解决方案的自由能，这不需要评估所有的内壳occupancy的模拟。
Here, we study quasi-chemical theory (QCT) for the free energies of divalent alkaline earth ions (Ba, Sr, Ca, Mg) in water, emphasizing that: (a) interactions between metal ions and proximal water molecules are as strong as traditional chemical effects; (b) QCT builds directly from accessible electronic structure calculations but rests on fully elaborated molecular statistical thermodynamics; (c) QCT offers choices of convenience in identifying coordination numbers for analysis. We investigate utilisation of direct QCT with inner-shell conditioning , alternative to the traditional conditioning motivated by a generalised vanderWaals view. The alternative works well: deleterious non-Gaussian effects of vanderWaals repulsive interactions are not serious, and the alternative conditioning improves the convenience of QCT calculations. Comparison between ab initio and force field molecular dynamics (AIMD and FFMD) with standard models suggests that FFMD likely exaggerates the anharmonicity in the thermal motion of inner-shell ion-water clusters. Together with the general encouraging support for the harmonic approximations implied by the conditioning, that observation helps explain the remarkable success of the cluster-based QCT solution free energies, which do not require assessment of all inner-shell occupancies by simulation.