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首页> 外文期刊>Acta Crystallographica, Section B. Structural science, crystal engineering and materials >Source Function applied to experimental densities reveals subtle electron-delocalization effects and appraises their transferability properties in crystals
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Source Function applied to experimental densities reveals subtle electron-delocalization effects and appraises their transferability properties in crystals

机译：源函数应用于实验密度揭示了细微的电子离域效应，并评估了它们在晶体中的转移性

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摘要

The Source Function (SF), introduced in 1998 by Richard Bader and Carlo Gatti, is succinctly reviewed and a number of paradigmatic applications to in vacuo and crystal systems are illustrated to exemplify how the SF may be used to discuss chemical bonding in both conventional and highly challenging cases. The SF enables the electron density to be seen at a point determined by source contributions from the atoms or a group of atoms of a system, and it is therefore well linked to the chemist's awareness that any local property and chemical behaviour is to some degree influenced by all the remaining parts of a system. The key and captivating feature of the SF is that its evaluation requires only knowledge of the electron density (ED) of a system, thereby enabling a comparison of ab initio and X-ray diffraction derived electron density properties on a common and rigorous basis. The capability of the SF to detect electrondelocalization effects and to quantify their degree of transferability is systematically explored in this paper through the analysis and comparison of experimentally X-ray derived Source Function patterns in benzene, naphthalene and (±)-8'-benzhydrylideneamino-1,1'-binaphthyl-2-ol (BAB) molecular crystals. It is shown that the SF tool recovers the characteristic SF percentage patterns caused by π-electron conjugation in the first two paradigmatic aromatic molecules in almost perfect quantitative agreement with those obtained from ab initio periodic calculations. Moreover, the effect of chemical substitution on the degree of transferability of such patterns to the benzene- and naphthalene-like moieties of BAB is neatly shown and quantified by the observed systematic deviations, relative to benzene and naphthalene, of only those SF contributions from the substituted C atoms. Finally, the capability of the SF to reveal electrondelocalization effects is challenged by using a promolecule density, rather than the proper quantum mechanical density, to determine the changes in SF patterns along the cyclohexene, 1,3-cyclohexadiene and benzene molecule series. It is shown that, differently from the proper quantum density, the promolecular density is unable to reproduce the SF trends anticipated by the increase of electron delocalization along the series, therefore ruling out the geometrical effect as being the only cause for the observed SF patterns changes.
机译：由理查德·巴德（Richard Bader）和卡洛·加蒂（Carlo Gatti）于1998年引入的源函数（SF）进行了简要回顾，并举例说明了在真空和晶体系统中的多种范例应用，以举例说明在传统方法和常规方法中如何使用SF来讨论化学键合。极富挑战性的案件。 SF使得可以在由系统原子或一组原子的源贡献确定的点上看到电子密度，因此它与化学家的认识紧密相关，化学家意识到任何局部性质和化学行为都会在一定程度上受到影响由系统的所有其余部分组成。 SF的关键和吸引人的特征是，其评估仅需要了解系统的电子密度（ED），从而可以在通用且严格的基础上比较从头算和X射线衍射得出的电子密度特性。通过分析和比较实验性X射线在苯，萘和（±）-8'-苯甲叉基氨基-中的X射线源函数图谱，系统地探索了SF检测电子离域效应并量化其转移程度的能力。 1,1'-联萘-2-醇（BAB）分子晶体。结果表明，SF工具可以恢复由头两个范例芳族分子中的π电子共轭引起的特征SF百分比模式，与从头算周期计算获得的结果几乎完全定量一致。此外，通过观察到的相对于苯和萘的系统偏差（仅来自SF的那些SF），可以清楚地显示和量化化学取代对此类图案向BAB的苯和萘样部分的转移性程度的影响。取代的C原子。最后，通过使用前分子密度而不是适当的量子力学密度来确定SF沿着环己烯，1,3-环己二烯和苯分子系列的变化，SF揭示电子离域作用的能力受到了挑战。结果表明，与适当的量子密度不同，前分子密度不能重现沿着系列的电子离域的增加所预期的SF趋势，因此排除了几何效应，这是观察到的SF模式变化的唯一原因。 。

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