Influence of intermolecular interactions on multipole-refined electron densities.
Influence of intermolecular interactions on multipole-refined electron densities.
复制标题
分子间相互作用对多极细化电子密度的影响。
DOI：
10.1107/s0108767398007181
复制
发表时间：
1999
期刊：
影响因子：
--
通讯作者：
K. Hermansson
中科院分区：
文献类型：
--
作者：
M. Spackman;P. G. Byrom;Maria Alfredsson;K. Hermansson
这项工作考察了分子间相互作用对从模拟x射线衍射数据得出的分子性质的影响。模型x射线数据是由晶体中从头算分子电子密度的叠加以及周期晶体Hartree-Fock电子密度计算得到的，适用于氢键系统ice VIII，甲酰胺和尿素，以及弱键乙炔。分子间相互作用对电子密度的影响在无限和有限数据分辨率下都得到了说明，并得出结论，尽管模型中的径向函数存在已知的缺点，但多极模型能够定量地检索相互作用密度。多极精化表明，氢键晶体的分子偶极矩显著增强，而分子秒矩的变化可以忽略不计。氢键作用下H核的电场梯度显著减小，刚性赝原子模型也忠实地反映了这一变化。
This work examines the effect of intermolecular interactions on molecular properties derived from simulated X-ray diffraction data. Model X-ray data are computed from a superposition of ab initio molecular electron densities in the crystal, as well as from periodic crystal Hartree-Fock electron densities, for the hydrogen-bonded systems ice VIII, formamide and urea, as well as the weakly bound acetylene. The effects of intermolecular interactions on the electron density are illustrated at both infinite and finite data resolution, and it is concluded that multipole models are capable of quantitative retrieval of the interaction density, despite the known shortcomings of the radial functions in the model. Multipole refinement reveals considerable enhancement of the molecular dipole moment for hydrogen-bonded crystals, and negligible change in molecular second moments. Electric field gradients at H nuclei are significantly reduced in magnitude upon hydrogen bonding, and this change is also faithfully represented by the rigid pseudoatom model.