The low-frequency (terahertz) dynamics of condensed phase materials provide valuable insight into numerous bulk phenomena. However, the assignment and interpretation of experimental results require computational methods due to the complex mode types that depend on weak intermolecular forces. Solid-state density functional theory has been used in this regard with great success, yet the selection of specific computational parameters, namely the chosen basis set and density functional, has a profound influence on the accuracy of predicted spectra. In this work, the role of these two parameters is investigated in a series of organic molecular crystals, in order to assess the ability of various methods to reproduce intermolecular forces, and subsequently experimental terahertz spectra. Specifically, naphthalene, oxalic acid, and thymine were chosen based on the varied intermolecular interactions present in each material. The results highlight that unconstrained geometry optimizations can be used as an initial proxy for the accuracy of interatomic forces, with errors in the calculated geometries indicative of subsequent errors in the calculated low-frequency vibrational spectra, providing a powerful metric for the validation of theoretical results. Finally, the origins of the observed shortcomings are analyzed, providing a basic framework for further studies on related materials.

凝聚相材料的低频（太赫兹）动力学提供了对众多块状现象的宝贵见解。然而，由于依赖于弱分子间力的复杂模式类型，实验结果的分配和解释需要计算方法。固态密度泛函理论在这方面已经获得了巨大的成功，但是特定计算参数的选择，即选择的基集和密度泛函，对预测光谱的准确性产生了深远的影响。在这项工作中，在一系列有机分子晶体中研究了这两个参数的作用，以评估各种方法再现分子间力以及随后的实验太赫兹光谱的能力。具体而言，萘，草酸，根据每种材料中存在的分子间相互作用，选择胸腺嘧啶和胸腺嘧啶。结果表明，无约束的几何优化可以用作表示原子间力准确性的初始指标，计算几何中的误差表示计算出的低频振动谱中的后续误差，为验证理论结果提供了有力的度量。最后，分析了所观察到的缺点的根源，为进一步研究相关材料提供了基本框架。计算出的几何形状中的误差表示计算出的低频振动谱中的后续误差，为验证理论结果提供了有力的度量。最后，分析了所观察到的缺点的根源，为进一步研究相关材料提供了基本框架。计算出的几何形状中的误差表示计算出的低频振动谱中的后续误差，为验证理论结果提供了有力的度量。最后，分析了所观察到的缺点的根源，为进一步研究相关材料提供了基本框架。