Exact two-component relativistic theory for NMR parameters: general formulation and pilot application.
Exact two-component relativistic theory for NMR parameters: general formulation and pilot application.
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DOI：
10.1063/1.4764042
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发表时间：
2012-11
期刊：
影响因子：
--
通讯作者：
Qiming Sun;Yunlong Xiao;Wenjian Liu
中科院分区：
文献类型：
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作者：
Qiming Sun;Yunlong Xiao;Wenjian Liu
先前提出的精确双组分（X2C）相对论核磁共振（NMR）参数理论[Q]。孙伟，刘伟，肖彦，程丽娟，化学。在矩阵和算子水平上，重新表述了以统一的方式容纳两种动力平衡方案，五种磁平衡方案和三种解耦方案。此外，在耦合摄动Kohn-Sham方程中考虑了自旋磁化的三种定义。除了简单之外，X2C-NMR最显著的特点在于它的抗磁性和顺磁性项在任何有限基下都与相应的四组分项单独一致。在实际应用中，介绍了一阶耦合矩阵X（10）的五种近似格式和处理双电子积分的四种近似格式，使X2C-NMR的计算与近似双组分方法的计算非常相似。
The previously proposed exact two-component (X2C) relativistic theory of nuclear magnetic resonance (NMR) parameters [Q. Sun, W. Liu, Y. Xiao, and L. Cheng, J. Chem. Phys. 131, 081101 (2009)] is reformulated to accommodate two schemes for kinetic balance, five schemes for magnetic balance, and three schemes for decoupling in a unified manner, at both matrix and operator levels. In addition, three definitions of spin magnetization are considered in the coupled-perturbed Kohn-Sham equation. Apart from its simplicity, the most salient feature of X2C-NMR lies in that its diamagnetic and paramagnetic terms agree individually with the corresponding four-component counterparts for any finite basis. For practical applications, five approximate schemes for the first order coupling matrix X(10) and four approximate schemes for the treatment of two-electron integrals are introduced, which render the computations of X2C-NMR very much the same as those of approximate two-component approaches.