Magnetic shielding constants calculated by the infinite-order Douglas-Kroll-Hess method with electron-electron relativistic corrections.
Magnetic shielding constants calculated by the infinite-order Douglas-Kroll-Hess method with electron-electron relativistic corrections.
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DOI：
10.1063/1.3413529
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发表时间：
2010-05
期刊：
影响因子：
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通讯作者：
Junji Seino;M. Hada
中科院分区：
文献类型：
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作者：
Junji Seino;M. Hada
提出了一个基于无限阶Douglas-Kroll（IODK）变换的磁屏蔽常数的双分量相对论量子化学理论。使用IODK变换也产生了双电子相对论修正，尽管忽略了小的项。小分量基函数的使用被完全排除在本理论之外。我们使用一阶Foldy-Wouthuysen（FW 1）、二阶Douglas-Kroll（DK2）和无限阶Douglas-Kroll（IODK）变换以及最低阶（c（-2））Breit-Pauli近似，研究了相对论单电子和双电子项以及磁相互作用项的能级组合。我们用FW 1、DK2、IODK和Breit-Pauli哈密顿量计算了几个闭壳层原子的磁屏蔽常数。IODK哈密顿量较好地再现了四分量Dirac-Fock-Coulomb理论的计算结果：最大偏差仅为2.2%。我们发现，单电子磁相互作用的相对论处理对磁屏蔽常数的准确性有很大影响，而双分量双电子相对论修正的影响相对较小。我们还讨论了图像变化对磁算符的影响。
We presented a two-component relativistic quantum-chemical theory for magnetic shielding constants, which is based on the infinite-order Douglas-Kroll (IODK) transformation. Two-electron relativistic corrections were also generated using the IODK transformation, although negligibly small terms were discarded. The use of small-component basis functions was completely excluded from the present theory. We examined the combination of the levels of relativistic one- and two-electron terms and magnetic interaction terms using the first-order Foldy-Wouthuysen (FW1), the second-order Douglas-Kroll (DK2), and the infinite-order Douglas-Kroll (IODK) transformations, as well as the lowest-order (c(-2)) Breit-Pauli approximation. We calculated the magnetic shielding constants of several closed-shell atoms using the FW1, DK2, IODK, and Breit-Pauli Hamiltonians. The IODK Hamiltonian reproduced well the results calculated by the four-component Dirac-Fock-Coulomb theory: The maximum deviation is only about 2.2%. We found that the accuracy of the magnetic shielding constants is strongly affected by the relativistic treatments of one-electron magnetic interaction, while the effect of the two-component two-electron relativistic corrections is relatively small. We also discussed the picture change effect on magnetic operators.