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Geometry relaxation has an opposite effect on the aromaticities of the \u03c0\u03c0* vertical T<jats:sub>1<\/jats:sub> and T<jats:sub>2<\/jats:sub>: The antiaromaticity of T<jats:sub>1<\/jats:sub> is reduced whereas the aromaticity of T<jats:sub>2<\/jats:sub> is enhanced. The shielding picture around T<jats:sub>2<\/jats:sub> is found to closely resemble those around certain second singlet \u03c0\u03c0* excited states (S<jats:sub>2<\/jats:sub>), for example, those of benzene and cyclooctatetraene, thought to be \u201cstrongly aromatic\u201d because of their very negative nucleus\u2010independent chemical shift (NICS) values. It is argued that while NICS values correctly follow the changes in aromaticity along the potential energy surface of a single electronic state, the use of NICS values for the purpose of quantitative comparisons between the aromaticities of different electronic states cannot be justified theoretically and should be avoided. \u201cStrongly aromatic\u201d S<jats:sub>2<\/jats:sub> and T<jats:sub>2<\/jats:sub> states should be referred to simply as \u201caromatic\u201d because detailed comparisons between the properties of these states and those of the corresponding S<jats:sub>0<\/jats:sub> states do not suggest higher levels of aromaticity.<\/jats:p>","DOI":"10.1002\/cphc.202400758","type":"journal-article","created":{"date-parts":[[2024,9,21]],"date-time":"2024-09-21T05:27:48Z","timestamp":1726896468000},"update-policy":"https:\/\/doi.org\/10.1002\/crossmark_policy","source":"Crossref","is-referenced-by-count":4,"title":["Aromaticity and Antiaromaticity Reversals between the Electronic Ground State and the Two Lowest Triplet States of Thiophene"],"prefix":"10.1002","volume":"26","author":[{"ORCID":"https:\/\/orcid.org\/0009-0009-5322-9961","authenticated-orcid":false,"given":"Edward","family":"Cummings","sequence":"first","affiliation":[{"name":"Department of Chemistry University of York  Heslington, York YO10 5DD UK"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-2673-6804","authenticated-orcid":false,"given":"Peter B.","family":"Karadakov","sequence":"additional","affiliation":[{"name":"Department of Chemistry University of York  Heslington, York YO10 5DD UK"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2024,11,5]]},"reference":[{"key":"e_1_2_9_1_1","doi-asserted-by":"publisher","DOI":"10.1021\/ja00769a025"},{"key":"e_1_2_9_2_1","doi-asserted-by":"publisher","DOI":"10.1002\/cplu.201800307"},{"key":"e_1_2_9_3_1","doi-asserted-by":"publisher","DOI":"10.1021\/acs.orglett.7b02257"},{"key":"e_1_2_9_4_1","doi-asserted-by":"publisher","DOI":"10.1002\/cptc.201800268"},{"key":"e_1_2_9_5_1","doi-asserted-by":"publisher","DOI":"10.1002\/anie.201802185"},{"key":"e_1_2_9_6_1","doi-asserted-by":"publisher","DOI":"10.1002\/anie.202006198"},{"key":"e_1_2_9_7_1","doi-asserted-by":"publisher","DOI":"10.1021\/jacs.0c05611"},{"key":"e_1_2_9_8_1","doi-asserted-by":"publisher","DOI":"10.1039\/C9CP02050K"},{"key":"e_1_2_9_9_1","doi-asserted-by":"publisher","DOI":"10.1039\/D0SC02294B"},{"key":"e_1_2_9_10_1","doi-asserted-by":"publisher","DOI":"10.1021\/cr300471v"},{"key":"e_1_2_9_11_1","doi-asserted-by":"publisher","DOI":"10.1039\/C5CS00057B"},{"key":"e_1_2_9_12_1","doi-asserted-by":"publisher","DOI":"10.1002\/chem.202203748"},{"key":"e_1_2_9_13_1","doi-asserted-by":"crossref","unstructured":"M. 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