Distinguishing between chemical bonding and physical binding using electron localization function (ELF)
Distinguishing between chemical bonding and physical binding using electron localization function (ELF)
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DOI：
10.1088/1361-648x/ab7fd8
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发表时间：
2020-07-22
影响因子：
2.7
通讯作者：
Larsson, J. Andreas
中科院分区：
文献类型：
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作者：
Koumpouras, Konstantinos;Larsson, J. Andreas
区分化学结合和物理结合通常很简单。在正常情况下，它们在相互作用强度(结合能)和相互作用长度(结构)上都不同。然而，化学键可能很弱(例如，在某些金属键中)，而物理结合可能很强(例如，由于永久性静电矩、氢结合等)，使得区别不是微不足道的。但由于它们分别是共享电子相互作用或非共享电子相互作用，因此原则上可以通过分析相互作用点(S)/界面周围的电子密度来区分相互作用的类型。毕竟，前者应该是一种接触，而后者应该是一种隧道屏障。在这里，我们在密度泛函理论的框架内研究了典型的分子和晶体，以显示电子局域函数(ELF)在不同共享电子相互作用中的行为，例如化学(共价)和金属键，并与典型的非共享电子相互作用，如离子、氢和Keesom，色散(Van Der Waals)结合，并试图仅根据ELF和相互作用区中的电子布居来分类。研究发现，ELF方法不仅对共价键的表征是有用的，而且对于较弱的键类型也可以提取大量信息。此外，在相互作用区(S)上的电荷积分和跟踪ELF轮廓可以揭示从三键到弱分散的键/键的强度。
To distinguish between chemical bonding and physical binding is usually simple. They differ, in the normal case, in both interaction strength (binding energy) and interaction length (structure). However, chemical bonding can be weak (e.g. in some metallic bonding) and physical binding can be strong (e.g. due to permanent electrostatic moments, hydrogen binding, etc) making differentiation non-trivial. But since these are shared-electron or unshared-electron interactions, respectively, it is in principle possible to distinguish the type of interaction by analyzing the electron density around the interaction point(s)/interface. After all, the former should be a contact while the latter should be a tunneling barrier. Here, we investigate within the framework of density functional theory typical molecules and crystals to show the behaviour of the electron localization function (ELF) in different shared-electron interactions, such as chemical (covalent) and metallic bonding and compare to unshared-electron interactions typical for physical binding, such as ionic, hydrogen and Keesom, dispersion (van der Waals) binding and attempt to categorise them only by the ELF and the electron population in the interaction region. It is found that the ELF method is not only useful for the characterization of covalent bonds but a lot of information can be extracted also for weaker types of binding. Furthermore, the charge integration over the interaction region(s) and tracing the ELF profile can reveal the strength of the bonding/binding ranging from the triple bonds to weak dispersion.