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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Calculation of N-15 and P-31 NMR Chemical Shifts of Azoles, Phospholes, and Phosphazoles: A Gateway to Higher Accuracy at Less Computational Cost
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Calculation of N-15 and P-31 NMR Chemical Shifts of Azoles, Phospholes, and Phosphazoles: A Gateway to Higher Accuracy at Less Computational Cost

机译：计算氮孔，磷含量，磷唑的N-15和P-31 NMR化学位移：在计算成本较少的高度准确度的网关

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摘要

A number of computational schemes for the calculation of N-15 and P-31 NMR chemical shifts and shielding constants in a series of azoles, phospholes, and phosphazoles was examined. A very good correlation between calculated at the CCSD(T) level and experimental N-15 and P-31 NMR chemical shifts was observed. It was found that basically solvent, vibrational, and relativistic corrections are of the same order of magnitude and alternate in sign, being, on average, of about 2-3 ppm in absolute value but, being much larger (up to 14 ppm) in the case of solvent molecules explicitly introduced into computational space. At the DFT level, the performance of nine exchange correlation functionals including six conventional gradient functionals and three hybrid functionals was studied. The most accurate results were reached with the OLYP and Keal-Tozer's family of functionals, KT1, KT2, and KT3, while the most popular B3LYP and PBE0 functionals showed the most unreliable results. On the basis of these data, we highly recommend OLYP and KT2 functionals for the computation of N-15 and P-31 NMR chemical shifts at the DFT level in the diverse series of nitrogen- and phosphorus-containing heterocycles. Benchmark calculations of N-15 and P-31 NMR chemical shifts in a series of larger nitrogen and phosphorus-containing heterocycles were performed at the DFT level in comparison with experiment and revealed the OLYP functional in combination with the aug-pcS-3/aug-pcS-2 locally dense basis set scheme as the most effective computational scheme.
机译：检查了一系列氮孔，磷脂中的N-15和P-31 NMR化学位移和屏蔽常数的许多计算方案。观察到在CCSD（T）水平和实验N-15和实验N-15和P-31 NMR化学变换之间的良好相关性。发现基本上溶剂，振动和相对论的校正具有相同的数量级和符号，平均值在绝对值中为约2-3ppm，但具有更大的（最多14ppm）明确引入计算空间的溶剂分子的情况。在DFT级别，研究了九个交换相关功能的性能，包括六种传统梯度函数和三个混合功能。最准确的结果与olyp和Keal-tozer的功能，KT1，KT2和KT3达成，而最受欢迎的B3Lyp和Pbe0功能显示出最不可靠的结果。在这些数据的基础上，我们强烈推荐olyp和Kt2功能，用于计算DFT水平的N-15和P-31 NMR化学位移，在不同系列的氮气和含磷杂环中的DFT水平。与实验相比，在DFT水平上进行N-15和P-31 NMR化学位移的N-15和P-31 NMR化学位移的基准计算，并揭示了与AUG-PCS-3/8月相结合的烯型功能-pcs-2本地密集基准设置方案作为最有效的计算方案。

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