The factors contributing to the accuracy of quantum‐chemical calculations for the prediction of proton NMR chemical shifts in molecular solids are systematically investigated. Proton chemical shifts of six solid amino acids with hydrogen atoms in various bonding environments (CH, CH₂, CH₃, OH, SH and NH₃) were determined experimentally using ultra‐fast magic‐angle spinning and proton‐detected 2D NMR experiments. The standard DFT method commonly used for the calculations of NMR parameters of solids is shown to provide chemical shifts that deviate from experiment by up to 1.5 ppm. The effects of the computational level (hybrid DFT functional, coupled‐cluster calculation, inclusion of relativistic spin‐orbit coupling) are thoroughly discussed. The effect of molecular dynamics and nuclear quantum effects are investigated using path‐integral molecular dynamics (PIMD) simulations. It is demonstrated that the accuracy of the calculated proton chemical shifts is significantly better when these effects are included in the calculations.

中文翻译：

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准确预测分子固体中质子NMR光谱参数。

系统地研究了影响量子化学计算准确性以预测分子固体中质子NMR化学位移的因素。在各种键合环境（CH，CH ₂，CH ₃，OH，SH和NH _3中）中六个具有氢原子的固体氨基酸的质子化学位移）是使用超快速魔角旋转和质子检测的2D NMR实验通过实验确定的。已显示通常用于计算固体NMR参数的标准DFT方法提供的化学位移最多偏离实验1.5 ppm。全面讨论了计算级别（混合DFT功能，耦合集群计算，相对论自旋轨道耦合的包含）的影响。使用路径积分分子动力学（PIMD）模拟研究了分子动力学和核量子效应的影响。结果表明，当将这些影响包括在计算中时，所计算的质子化学位移的准确性会明显提高。