Fast and Accurate Electric Field Gradient Calculations in Molecular Solids With Density Functional Theory.
Fast and Accurate Electric Field Gradient Calculations in Molecular Solids With Density Functional Theory.
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DOI：
10.3389/fchem.2021.751711
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发表时间：
2021
影响因子：
5.5
通讯作者：
Harper JK
中科院分区：
文献类型：
--
作者：
Hartman JD;Mathews A;Harper JK
计算分子固体中电场梯度张量的现代方法依赖于使用周期边界条件(PBC)的平面波计算。在实践中，使用PBC的模型仅限于广义梯度近似(GGA)密度泛函。在规范-包括原子轨道(GIAO)计算中应用的混合密度泛函已被证明显著提高了预测的核磁共振参数的准确性。在这里，我们提出了一种有效的方法，它有效地结合了周期计算和单分子技术的优点，用于预测分子固体中的电场梯度张量。使用平面波基组的周期计算来模拟结晶环境。然后，我们引入了一个分子修正的周期结果，从单分子计算执行的杂化密度泛函。使用杂化密度泛函进行的单分子计算发现，预测的17O四极耦合常数(CQ)与实验的一致性显著提高。我们使用由22个含氧分子晶体组成的精心构建的测试集，证明了与标准平面波方法相比，预测的17O C Q值的均方根误差降低了31%。使用五种不同的杂化密度泛函，我们发现预测的CQ值对单分子计算中使用的基组的选择相对不敏感。最后，以4-硝基苯甲醛的无序晶体结构为例，说明了高精度的17O-C-Q预测的实用性。
Modern approaches for calculating electric field gradient (EFF) tensors in molecular solids rely upon plane-wave calculations employing periodic boundary conditions (PBC). In practice, models employing PBCs are limited to generalized gradient approximation (GGA) density functionals. Hybrid density functionals applied in the context of gauge-including atomic orbital (GIAO) calculations have been shown to substantially improve the accuracy of predicted NMR parameters. Here we propose an efficient method that effectively combines the benefits of both periodic calculations and single-molecule techniques for predicting electric field gradient tensors in molecular solids. Periodic calculations using plane-wave basis sets were used to model the crystalline environment. We then introduce a molecular correction to the periodic result obtained from a single-molecule calculation performed with a hybrid density functional. Single-molecule calculations performed using hybrid density functionals were found to significantly improve the agreement of predicted 17O quadrupolar coupling constants (C q ) with experiment. We demonstrate a 31% reduction in the RMS error for the predicted 17O C q values relative to standard plane-wave methods using a carefully constructed test set comprised of 22 oxygen-containing molecular crystals. We show comparable improvements in accuracy using five different hybrid density functionals and find predicted C q values to be relatively insensitive to the choice of basis set used in the single molecule calculation. Finally, the utility of high-accuracy 17O C q predictions is demonstrated by examining the disordered 4-Nitrobenzaldehyde crystal structure.