Structures and Heats of Formation of Simple Alkaline Earth Metal Compounds II: Fluorides, Chlorides, Oxides, and Hydroxides for Ba, Sr, and Ra.
Structures and Heats of Formation of Simple Alkaline Earth Metal Compounds II: Fluorides, Chlorides, Oxides, and Hydroxides for Ba, Sr, and Ra.
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DOI：
10.1021/acs.jpca.7b09056
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发表时间：
2018
期刊：
影响因子：
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通讯作者：
Monica Vasiliu;J. G. Hill;Kirk A. Peterson;David A. Dixon
中科院分区：
文献类型：
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作者：
Monica Vasiliu;J. G. Hill;Kirk A. Peterson;David A. Dixon
在耦合簇理论CCSD(T)水平上预测了晚期碱土（Sr、Ba和Ra）氧化物、氟化物、氯化物和氢化物的几何参数、振动频率、形成热、键解能、内聚能和选定的氟化物亲和（二氟化物）。附加的修正（标量相对论和伪势修正、振动零点能量和原子自旋轨道效应）被包括在内，以精确地计算总原子化能和形成热。将计算值与实验数据进行了比较。在某些情况下，特别是对于Ra化合物，没有实验结果，或者实验的能量学和几何形状不可靠或有很大的误差。所有的Sr、Ba和Ra二氟化物、二氯化物和二氢氧化物都是弯曲结构，OMO键角沿着基团递减。预测大块二卤化Be的内聚能较低，而Ra的内聚能较大。氟亲和表明，二氟化物是中等强度的路易斯酸，这种三氟化物可以在适当的实验条件下形成。
Geometry parameters, vibrational frequencies, heats of formation, bond dissociation energies, cohesive energies, and selected fluoride affinities (difluorides) are predicted for the late alkaline earth (Sr, Ba, and Ra) oxides, fluorides, chlorides, and hydroxides at the coupled cluster theory CCSD(T) level. Additional corrections (scalar relativistic and pseudopotential corrections, vibrational zero-point energies, and atomic spin-orbit effects) were included to accurately calculate the total atomization energies and heats of formation following the Feller-Peterson-Dixon methodology. The calculated values are compared to the experimental data where available. In some cases, especially for Ra compounds, there are no experimental results, or the experimental energetics and geometries are not reliable or have very large error bars. All of the Sr, Ba, and Ra difluorides, dichlorides, and dihydroxides are bent structures with the OMO bond angles decreasing going down the group. The cohesive energies of bulk Be dihalides are predicted to be quite low, while those of Ra are relatively large. The fluoride affinities show that the difluorides are moderately strong Lewis acids and that such trifluorides may form under the appropriate experimental conditions.