Exotic Bonding Regimes Uncovered in Excited States |
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Authors: | José Luis Casals-Sainz Prof. Jesús Jara-Cortés Prof. Jesús Hernández-Trujillo José Manuel Guevara-Vela Prof. Evelio Francisco Prof. Ángel Martín Pendás |
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Affiliation: | 1. Departamento de Química FisicayAnalítica, Facultad de Química, Universidad de Oviedo, 33006 Oviedo, Spain;2. Unidad Académica de Ciencias Básicas e Ingenierias, Universidad Autónoma de Nayarit, Tepic, 63155 México;3. Departmento de Física y Química Teórica, Facultad de Química, UNAM, México City, 04510 México |
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Abstract: | Real-space tools were employed to show that the chemical bonding scenario used routinely to understand ground states lacks the necessary flexibility in excited states. It is shown that, even for two-center, two-electron bonds, the real-space bond orders have exotic values that have never been reported. The nature of these situations was uncovered by using electron-counting techniques that provide an appealing statistical interpretation of bonding descriptors, together with simple physical models. Bond orders greater than one as well as negative bond orders for a single bonding electron pair emerge in situations in which the electrons in the pair show a gregarious (bosonic) instead of the usual lonely (fermionic) behavior. In the first case the gregarious pair is intra-atomic, whereas the coupling is interatomic in the second. A number of examples are used to substantiate these claims. |
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Keywords: | ab initio calculations bond theory electronic structures excited states quantum chemistry |
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