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Identification and Characterization of Molecular Bonding Structures by ab initio Quasi-Atomic Orbital Analyses

TitleIdentification and Characterization of Molecular Bonding Structures by ab initio Quasi-Atomic Orbital Analyses
Publication TypeJournal Article
Year of Publication2017
AuthorsWest, AC, Duchimaza-Heredia, JJ, Gordon, MS, Ruedenberg, K
JournalJournal of Physical Chemistry A
Volume121
Pagination8884-8898
Date Published11
Type of ArticleArticle
ISBN Number1089-5639
Accession NumberWOS:000416495300015
Keywordschemistry, comprehensive analysis, consistent-field method, density-matrix, electronic wave-functions, energy decomposition, fully-variational optimization, intrinsic local constituents, minimal basis-sets, physics, population analysis, transition-state method
Abstract

The quasi-atomic analysis of ab initio electronic wave functions in full valence spaces, which was developed in preceding papers, yields oriented quasi-atomic orbitals in terms of which the ab initio molecular wave function and energy can be expressed. These oriented quasi-atomic orbitals are the rigorous ab initio counterparts to the conceptual bond forming atomic hybrid orbitals of qualitative chemical reasoning. In the present work, the quasi-atomic orbitals are identified as bonding orbitals, lone pair orbitals, radical orbitals, vacant orbitals and orbitals with intermediate character. A program determines the bonding characteristics of all quasi-atomic orbitals in a molecule on the basis of their occupations, bond orders, kinetic bond orders, hybridizations and local symmetries. These data are collected in a record and provide the information for a comprehensive understanding of the synergism that generates the bonding structure that holds the molecule together. Applications to a series of molecules exhibit the complete bonding structures that are embedded in their ab initio wave functions. For the strong bonds in a molecule, the quasi-atomic orbitals provide quantitative ab initioamplifications of the Lewis dot symbols. Beyond characterizing strong bonds, the quasi-atomic analysis also yields an understanding of the weak interactions, such as vicinal, hyperconjugative and radical stabilizations, which can make substantial contributions to the molecular bonding structure.

DOI10.1021/acs.jpca.7b07054
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Chemical Physics