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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >~(14,15)N NMR Shielding Constants from Density Functional Theory
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~(14,15)N NMR Shielding Constants from Density Functional Theory

机译：来自密度泛函理论的〜（14,15）N NMR屏蔽常数

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摘要

The prediction of nuclear magnetic resonance (NMR) shielding parameters for the N atom represents a particularly difficult task for most of the Hartree-Fock (HF)-based or density functional theory (DFT)-based methologies. In fact, for some molecular systems, the effect of the presence of a lone pair and multiple bonds on the N atom makes the use of higher correlated methods absolutely necessary to obtain accurate results. In this article, we present an extensive study covering almost the entire spectrum of nitrogen shielding, from + 400 to -50 ppm. The sum-over-states density functional perturbation theory (SOS-DFPT) has been used to calculate the shielding constant of 132 different N atoms. The potential of the various SOS-DFPT local approximations has been assessed through the comparison of N atoms that belong to similar molecular systems to experimental data. This procedure allows us to determine the margin of error to be considered in the SOS-DFPT calculation of the isotropic shieldings for each type of N atom.
机译：对于大多数基于Hartree-Fock（HF）或基于密度泛函理论（DFT）的方法论，对于N原子的核磁共振（NMR）屏蔽参数的预测是一项特别困难的任务。实际上，对于某些分子系统，孤对和多个键的存在对N原子的影响使得必须使用更高相关性的方法来获得准确的结果。在本文中，我们将进行广泛的研究，涵盖几乎所有的氮屏蔽光谱，从+ 400到-50 ppm。状态总和密度泛函摄动理论（SOS-DFPT）已用于计算132个不同N原子的屏蔽常数。通过将属于相似分子系统的N原子与实验数据进行比较，评估了各种SOS-DFPT局部逼近的潜力。此过程使我们能够确定在针对每种N原子的各向同性屏蔽的SOS-DFPT计算中要考虑的误差范围。

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