Anisotropic displacement parameters from dispersion-corrected DFT methods and their experimental validation by temperature-dependent X-ray diffraction
Anisotropic displacement parameters from dispersion-corrected DFT methods and their experimental validation by temperature-dependent X-ray diffraction
复制标题
DOI：
10.1039/c5ce01219h
复制
发表时间：
2015-09
期刊：
影响因子：
3.1
通讯作者：
Janine George;Ai Wang;Volker L. Deringer;Ruimin Wang;R. Dronskowski;U. Englert
中科院分区：
文献类型：
--
作者：
Janine George;Ai Wang;Volker L. Deringer;Ruimin Wang;R. Dronskowski;U. Englert
在化学结晶学中，散射中心的热运动通常用各向异性位移参数(ADPs)来描述。最近，研究表明，ADP不仅可以通过衍射实验获得，而且还可以通过理论获得：这种新兴的方法似乎很有希望，但必须进行彻底的测试。在这项研究中，我们在100到300K之间进行了专门定制的X射线衍射实验，这些实验允许与色散校正密度泛函理论(DFT)结合周期晶格动力学的从头计算数据进行详细的比较。本研究选用的晶体五氯吡啶(C5NCl5)非常适合于这一目的：它代表的是不含氢原子的分子晶体，因此不会对X射线衍射构成挑战；它的固态结构受分散和卤素键相互作用控制；与外围氯原子相关的ADP表现出强烈的温度依赖性。直接空间和倒数空间的质量标准证明，在100-200K的温度范围内，ADP的预测具有很高的置信度，并且DFT的几个经济色散校正可以可靠地用于此目的。在我们这里探索的范围内，ADPs的从头算预测似乎是一种简便和补充的工具，特别是在那些衍射数据不能提供直接的热运动模型的情况下。
In chemical crystallography, the thermal motion of scattering centres is commonly described by anisotropic displacement parameters (ADPs). Very recently, it has been shown that ADPs are not only accessible by diffraction experiments but also via theory: this emerging approach seems promising but must be thoroughly tested. In this study, we have performed specifically tailored X-ray diffraction (XRD) experiments in fine steps between 100 and 300 K which allow detailed comparison to ab initio data from dispersion-corrected density functional theory (DFT) combined with periodic lattice-dynamics. The compound chosen for this study, crystalline pentachloropyridine (C5NCl5), is well suited for this purpose: it represents a molecular crystal without H atoms, thus posing no challenge to XRD; its solid-state structure is controlled by dispersion and halogen-bonding interactions; and the ADPs associated with the peripheral Cl atoms show strong temperature dependence. Quality criteria in direct and in reciprocal space prove that ADPs are predicted with high confidence for the temperature range between 100 and 200 K, and that several economic dispersion corrections to DFT can be reliably employed for this purpose. Within the limits we have explored here, the ab initio prediction of ADPs appears to be a facile and complementary tool, especially in those cases where diffraction data cannot provide a straightforward model for thermal motion.