Experimental charge densities and intermolecular interactions: Electrostatic and topological analysis of DL-histidine
Experimental charge densities and intermolecular interactions: Electrostatic and topological analysis of DL-histidine
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DOI：
10.1021/ja983320f
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发表时间：
1999-03-24
影响因子：
15
通讯作者：
Pressprich, MR
中科院分区：
文献类型：
--
作者：
Coppens, P;Abramov, Y;Pressprich, MR
一个高分辨率，低温X射线衍射数据集博士组氨酸，收集与CCD检测器，用于分子键合和分子间相互作用的分析。晶体中的分子偶极矩相对于HF和DFT计算得到的分子偶极矩有所增强。分子电子密度的拓扑性质与极性键的理论不同，但通常与分子中的C-C键一致。研究的一个主要目的是从实验密度的分子间相互作用的静电贡献的评价。从实验密度计算的相邻分子对之间的静电相互作用能与超分子计算的总相互作用能相当好地比较。通过增加非静电排斥和色散项，该协议有所改善，它们共同贡献比静电能量少得多。从CHARMM点电荷力场计算的静电相互作用能通常接近从实验电荷密度导出的值，但也有例外。在另一种方法中，分子间电荷密度的拓扑结构与分子间相互作用能有关。后一种方法利用Abramov的密度泛函（Acta Crystallogr. 1997，A53，264-272）和键临界点处的势能密度与氢键解离能之间的关系（埃斯皮诺萨等人，Chem. Phys. Lett. 1998，285，170-173）。
A high-resolution, low-temperature X-ray diffraction data set on Dr-histidine, collected with a CCD detector, is used in the analysis of molecular bonding and intermolecular interactions. The molecular dipole moment in the crystal is enhanced relative to that from HF and DFT calculations. Topological properties of the molecular electron density differ from theory for the polar bonds but generally agree well for the C-C bonds in the molecule. A major aim of the study is the evaluation of the electrostatic contribution to the intermolecular interactions from the experimental density. The electrostatic interaction energies between pairs of neighboring molecules, as calculated from the experimental density, compare reasonably well with the total interaction energies from supermolecule calculations. The agreement is somewhat improved by the addition of nonelectrostatic repulsion and dispersive terms, which together contribute much less than the electrostatic energy. The electrostatic interaction energy calculated from the CHARMM point-charge force field is often close to the values derived from the experimental charge density, though exceptions occur. In an alternative approach, the topology of the intermolecular charge density is related to the intermolecular interaction energy. The latter approach makes use of a density functional by Abramov (Acta Crystallogr. 1997, A53, 264-272) and a relation between the potential energy density at the bond critical point and the hydrogen bond dissociation energy (Espinosa, et al. Chem. Phys. Lett. 1998, 285, 170-173).