Can simple ‘molecular’ corrections outperform projector augmented-wave density functional theory in the prediction of 35Cl electric field gradient tensor parameters for chlorine-containing crystalline systems?
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引用次数: 0
Abstract
Many-body expansion (MBE) fragment approaches have been applied to accurately compute nuclear magnetic resonance (NMR) parameters in crystalline systems. Recent examples demonstrate that electric field gradient (EFG) tensor parameters can be accurately calculated for 14N and 17O. A key additional development is the simple molecular correction (SMC) approach, which uses two one-body fragment (i.e., isolated molecule) calculations to adjust NMR parameter values established using ‘benchmark’ projector augmented-wave (PAW) density functional theory (DFT) values. Here, we apply a SMC using the hybrid PBE0 exchange-correlation (XC) functional to see if this can improve the accuracy of calculated 35Cl EFG tensor parameters. We selected eight organic and two inorganic crystal structures and considered 15 chlorine sites. We find that this SMC improves the accuracy of computed values for both the 35Cl quadrupolar coupling constant (CQ) and the asymmetry parameter (
) by approximately 30% compared with benchmark PAW DFT values. We also assessed a SMC that offers local improvements not only in terms of the quality of the XC functional but simultaneously in the quality of the description of relativistic effects via the inclusion of spin–orbit effects. As the inorganic systems considered contain heavy atoms bonded to the chlorine atoms, we find further improvements in the accuracy of calculated 35Cl EFG tensor parameters when both a hybrid functional and spin–orbit effects are included in the SMC. On the contrary, for chlorine-containing organics, the inclusion of spin–orbit relativistic effects using a SMC does not improve the accuracy of computed 35Cl EFG tensor parameters.
多体展开(MBE)碎片法已被应用于晶体体系核磁共振参数的精确计算。最近的例子表明,电场梯度(EFG)张量参数可以精确地计算14 N和17 o。一个关键的附加发展是简单分子校正(SMC)方法,它使用两个单体片段(即孤立分子)计算来调整使用“基准”投影增强波(PAW)密度函数理论(DFT)值建立的核磁共振参数值。在这里,我们使用混合PBE0交换相关(XC)函数应用SMC,看看这是否可以提高计算35 Cl EFG张量参数的准确性。我们选择了8种有机晶体结构和2种无机晶体结构,并考虑了15个氯位。我们发现,该SMC将35 Cl四极耦合常数(CQ)和不对称参数(η Q $$ {\eta}_{\mathrm{Q}} $$)的计算值的精度提高了约30% compared with benchmark PAW DFT values. We also assessed a SMC that offers local improvements not only in terms of the quality of the XC functional but simultaneously in the quality of the description of relativistic effects via the inclusion of spin-orbit effects. As the inorganic systems considered contain heavy atoms bonded to the chlorine atoms, we find further improvements in the accuracy of calculated 35 Cl EFG tensor parameters when both a hybrid functional and spin-orbit effects are included in the SMC. On the contrary, for chlorine-containing organics, the inclusion of spin-orbit relativistic effects using a SMC does not improve the accuracy of computed 35 Cl EFG tensor parameters.
期刊介绍:
MRC is devoted to the rapid publication of papers which are concerned with the development of magnetic resonance techniques, or in which the application of such techniques plays a pivotal part. Contributions from scientists working in all areas of NMR, ESR and NQR are invited, and papers describing applications in all branches of chemistry, structural biology and materials chemistry are published.
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