Aqueous Solvation of SmI2: A Born-Oppenheimer Molecular Dynamics Density Functional Theory Cluster Approach.
Aqueous Solvation of SmI2: A Born-Oppenheimer Molecular Dynamics Density Functional Theory Cluster Approach.
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SmI2 的水溶剂化：玻恩-奥本海默分子动力学密度泛函理论簇方法。
DOI：
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发表时间：
2017
影响因子：
2.9
通讯作者：
L. Maron
中科院分区：
文献类型：
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作者：
A. Ramı Rez;J. I. Amaro;J. Hernández;L. Maron
我们报告的结果Born-Oppenheimer分子动力学（BOMD）模拟的水溶剂化的SmI 2分子在室温下使用簇微溶剂化方法，包括32个水分子。电子结构计算使用M062 X混合交换相关泛函结合6- 31 G ** 基组对氧和氢进行。对于碘和钐原子，利用了斯图加特-科隆相对论有效核势及其相关的价基组。从优化的几何形状的SmI 2嵌入在微溶剂化环境中，我们发现了一个快速的取代碘离子周围的Sm（II）的8个紧密结合的水分子。通过Sm-O径向分布函数和Sm-O距离的演化，本研究预测了第一个刚性Sm（II）溶剂化壳层从2.6到3.4 μ m，其积分导致8.4个水分子的配位数，和第二个较软的溶剂化球从3.5到约。六尺。Sm（II）-O径向分布函数与EXAFS研究中报道的Sr 2+的径向分布函数非常一致，这一事实可以解释为Sr 2+和Sm 2+具有几乎相同的离子半径（约100 nm）。1.26 Sr ~（2+）的配位数为8，Sm ~（2+）的配位数为8.4。从BOMD轨道获得的理论EXAFS光谱，并讨论了Sm（III）的实验光谱的光。一旦实现微溶剂化，没有水交换事件被发现发生在Sm 2+周围，与Eu 2+的实验数据（其具有与Sm 2+几乎相同的电荷-离子半径关系）一致，其中水分子在[Eu（H2O）8]2+中的平均停留时间已知为约1.5小时。230 ps。
We report the results of Born-Oppenheimer molecular dynamics (BOMD) simulations on the aqueous solvation of the SmI2 molecule at room temperature using the cluster microsolvation approach including 32 water molecules. The electronic structure calculations were done using the M062X hybrid exchange-correlation functional in conjunction with the 6-31G** basis sets for oxygen and hydrogen. For the iodine and samarium atoms the Stuttgart-Köln relativistic effective-core potentials were utilized with their associated valence basis sets. Starting from the optimized geometry of SmI2 embeded in the microsolvation environment, we find a swift substitution of the iodine ions by eight tightly bound water molecules around Sm(II). Through the Sm-O radial distribution function and the evolution of the Sm-O distances, the present study predicts a first rigid Sm(II) solvation shell from 2.6 to 3.4 Å, whose integration leads to a coordination number of 8.4 water molecules, and a second softer solvation sphere from 3.5 to ca. 6 Å. The Sm(II)-O radial distribution function is in excellent agreement with that reported for Sr2+ from EXAFS studies, a fact that can be explained because Sr2+ and Sm2+ have almost identical ionic radii (ca. 1.26 Å) and coordination numbers: 8 for Sr2+ and 8.4 for Sm2+. The theoretical EXAFS spectrum was obtained from the BOMD trajectory and is discussed in the light of the experimental spectra for Sm(III). Once microsolvation is achieved, no water exchange events were found to occur around Sm2+, in agreement with the experimental data for Eu2+ (which has a nearly identical charge-to-ionic radius relation as Sm2+), where the mean residence time of a water molecule in [Eu(H2O)8]2+ is known to be ca. 230 ps.