The role of the exchange-correlation response kernel and scaling corrections in relativistic density functional nuclear magnetic shielding calculations with the zeroth-order regular approximation
The role of the exchange-correlation response kernel and scaling corrections in relativistic density functional nuclear magnetic shielding calculations with the zeroth-order regular approximation
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DOI：
10.1080/00268976.2013.796415
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发表时间：
2013-09-01
影响因子：
1.7
通讯作者：
Autschbach, Jochen
中科院分区：
文献类型：
--
作者：
Autschbach, Jochen
阿姆斯特丹密度泛函（ADF）软件包，这是经常使用的重原子NMR化学位移的研究中的相对论NMR模块，被扩展到计算一个迄今被忽视的长期从交换相关（XC）势的响应。在没有自旋-轨道耦合的情况下，该项消失。此外，在零阶正则近似（zora）相对论框架中的屏蔽所产生的标度因子的修正进行了研究。XC响应显着改善了卤化氢的质子化学位移计算值。二卤化汞的汞化学位移也明显改变。响应核中密度梯度相关项的贡献约为30- 40%。新的完全相对论密度泛函理论（DFT）基准数据与zora和文献参考值进行了比较。在与以前的工作，它被发现，绝对屏蔽常数汞不准确预测与佐拉。然而，化学位移与完全相对论计算吻合得很好。scaled-zora的比例因子的应用恶化了屏蔽常数，因此不推荐使用。标度几乎不影响化学位移。Zora计算不适用于重原子的绝对屏蔽，但它们可以安全地用于大多数应用场景中的化学位移。
The relativistic NMR module of the Amsterdam Density Functional (ADF) package, which is frequently utilised in studies of heavy atom NMR chemical shifts, is extended to calculate a hitherto neglected term from the response of the exchange-correlation (XC) potential. The term vanishes in the absence of spin-orbit coupling. Further, corrections to the shielding arising from scaling factors in the zeroth-order regular approximation (zora) relativistic framework are investigated. The XC response markedly improves calculated proton chemical shifts for hydrogen halides. Mercury chemical shifts for mercury dihalides are also noticeably altered. Contributions from density-gradient dependent terms in the response kernel contribute about 30-40%. New fully relativistic density functional theory (DFT) benchmark data are compared with zora and literature reference values. In line with previous work, it is found that absolute shielding constants for Hg are not accurately predicted with zora. However, chemical shifts agree well with fully relativistic calculations. The application of scaled-zora' scaling factors deteriorates the shielding constants and is therefore not recommended. The scaling hardly affects chemical shifts. zora calculations are not suitable for absolute shielding of heavy atoms but they can be used safely for chemical shifts in most application scenarios.