Azam S Sikander, Hofer Thomas S, Bhattacharjee Anirban, Lim Len Herald V, Pribil Andreas B, Randolf Bernhard R, Rode Bernd M
Theoretical Chemistry Division, Institute of General, Inorganic and Theoretical Chemistry, University of Innsbruck, Innrain 52a, A-6020 Innsbruck, Austria.
J Phys Chem B. 2009 Jul 9;113(27):9289-95. doi: 10.1021/jp903536k.
A quantum mechanical charge field (QMCF) molecular dynamics (MD) simulation including the first and second hydration shells in the QM region has been carried out to describe the structural and dynamical properties of Be(2+) in aqueous solution. In this methodology, the full first and second hydration shells are treated by ab initio quantum mechanics supplemented by a fluctuating electrostatic embedding technique. From the simulation, structural properties were extracted and were found to be in good agreement with previously published experimental and theoretical results. The radial distribution function (RDF) showed the maximum probability of the Be-O bond length at 1.62 A. The first tetrahedrally arranged hydration shell is highly inert with respect to ligand-exchange processes. Application of local-density-corrected three-body correlation analysis showed minor structural influence of the ion beyond the second hydration layer, contrary to the findings of a previous QM/MM MD simulation. The dynamics of the hydrate were studied in terms of ligand mean residence times (MRTs) and the power spectrum of the Be(2+)-O stretching frequency. A comparison of the "classical" QM/MM framework with the QMCF method clearly demonstrated the advantages of the latter, as ambiguities arising from the coupling of the subregions occurring in QM/MM MD simulations did not appear when the QMCF ansatz was applied.
已经进行了一种量子力学电荷场（QMCF）分子动力学（MD）模拟，该模拟在QM区域中包含第一和第二水合层，以描述水溶液中Be(2+)的结构和动力学性质。在这种方法中，完整的第一和第二水合层通过从头算量子力学并辅以波动静电嵌入技术来处理。从模拟中提取了结构性质，发现其与先前发表的实验和理论结果高度吻合。径向分布函数（RDF）显示Be-O键长在1.62 Å处具有最大概率。相对于配体交换过程，第一个四面体排列的水合层具有高度惰性。局部密度校正三体相关分析的应用表明，与之前QM/MM MD模拟的结果相反，离子对第二水合层之外的结构影响较小。根据配体平均停留时间（MRTs）和Be(2+)-O伸缩频率的功率谱研究了水合物的动力学。“经典”QM/MM框架与QMCF方法的比较清楚地证明了后者的优势，因为当应用QMCF假设时，QM/MM MD模拟中出现的子区域耦合所产生的模糊性并未出现。
