A Benchmark Study of Aromaticity Indexes for Benzene, Pyridine, and the Diazines-II. Excited State Aromaticity

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In this work, one geometrical aromaticity index and four electron sharing indexes are benchmarked for their application in excited state aromaticity calculations. Two computationally feasible and reliable procedures are identified, namely, CAM-B3LYP/cc-pVTZ and omega B97X-D/cc-pVTZ. Topological effects on the first excited singlet and triplet electronic manifold were investigated, and the latter was in general found to display more aromatic character compared to the S1 surface. Besides, geometrical relaxation on each of the manifolds was observed to hamper the aromaticity, thereby resulting in more antiaromatic character. The relative order of excited state aromaticity within the studied molecules was noted to resemble the reversed version of the relative order of ground state aromaticity. Thereby, the following generalization was postulated: The more aromatic a molecule is in its ground state, the more antiaromatic it will be in its electronic first excited manifolds.

Original languageEnglish
JournalJournal of Physical Chemistry A
Volume127
Issue number1
Pages (from-to)122–130
Number of pages9
ISSN1089-5639
DOIs
Publication statusPublished - 2023

    Research areas

  • DENSITY-FUNCTIONAL THEORY, GAUSSIAN-BASIS SETS, CORRELATED MOLECULAR CALCULATIONS, QUADRATIC RESPONSE FUNCTIONS, ELECTRON DELOCALIZATION, ORGANIC-PHOTOCHEMISTRY, ORBITAL METHODS, GROUND-STATE, ATOMS, ANTIAROMATICITY

ID: 332036179