Calculation of chemical-shift tensors of heavy nuclei: a DFT/ZORA investigation of 199 Hg chemical-shift tensors in solids, and the effects of cluster size and electronic-state approximations
Calculation of chemical-shift tensors of heavy nuclei: a DFT/ZORA investigation of 199 Hg chemical-shift tensors in solids, and the effects of cluster size and electronic-state approximations
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重核化学位移张量的计算：固体中 199 Hg 化学位移张量的 DFT/ZORA 研究，以及团簇尺寸和电子态近似的影响
DOI：
10.1039/c4cp01682c
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
Dybowski, C.
中科院分区：
文献类型：
--
作者：
Alkan, Fahri;Dybowski, C.
使用各种结构簇模型计算一组含汞材料的核磁共振化学屏蔽张量，为形成模型和使用各种方法进行计算的程序提供了严格的测试。分子簇中包含更高配位的壳层，使得 199Hg 化学屏蔽张量元素的量子化学计算误差在实验值的 3% 以内。我们证明，通过仔细引入冻结核心近似，可以减少计算成本高昂的分子簇计算的规模，同时对计算的 NMR 参数影响有限。分子簇方法证明了相对论哈密顿量对于准确预测化学屏蔽值的重要性。结果表明，仔细设计代表固态结构的簇、至少在自旋轨道水平上将相对论成分包含在哈密顿量中以及明智地使用近似值对于获得与实验结果的良好一致性至关重要。
Calculations of the nuclear magnetic resonance chemical-shielding tensors of a suite of mercury-containing materials using various cluster models for the structures provide a stringent test of the procedures for forming models and for calculation with various methods. The inclusion of higher co-ordination shells in the molecular clusters permits quantum chemical calculations of 199Hg chemical-shielding tensor elements within 3% of the experimental values. We show that it is possible to reduce the size of computationally expensive molecular-cluster calculations with limited effect on calculated NMR parameters by carefully introducing the frozen core approximation. The importance of the relativistic Hamiltonian for accurate predictions of chemical-shielding values is demonstrated within the molecular cluster approach. The results demonstrate that careful design of a cluster to represent the solid-state structure, inclusion of relativistic components in the Hamiltonian at least at the spin–orbit level, and judicious use of approximations are essential to obtain good agreement with experimental results.