{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,9]],"date-time":"2026-03-09T05:40:29Z","timestamp":1773034829324,"version":"3.50.1"},"reference-count":18,"publisher":"Wiley","issue":"3","license":[{"start":{"date-parts":[[2004,9,7]],"date-time":"2004-09-07T00:00:00Z","timestamp":1094515200000},"content-version":"vor","delay-in-days":3478,"URL":"http:\/\/onlinelibrary.wiley.com\/termsAndConditions#vor"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["J Comput Chem"],"published-print":{"date-parts":[[1995,3]]},"abstract":"<jats:title>Abstract<\/jats:title><jats:p><jats:italic>Ab initio<\/jats:italic> calculations on the structure of pyrazole have been carried out at different levels of accuracy. At the Hartree\u2010Fock (HF) level, the performance of several basis sets, namely 3\u201021G, 6\u201031G, 6\u201031G**, and 6\u2013311G** was investigated. The influence of electron correlation effects also was studied by carrying out geometry optimizations at the MP2, MP4, and QCISD levels. The performance of a density functional method also was evaluated. We have also investigated the possible influence of the frozen core approximation on the final optimized geometry. Three different statistical analyses were considered in determining which geometry is closest to the experimental microwave geometry\u2014namely Paul Curtin's diagrams, cluster analysis, and multidimensional scaling. From these analyses, we conclude that there is no asymptotic approach to the experimental geometry by increasing the quality of the theoretical model, although, as expected, the more reliable structures are those obtained at the MP2, MP4, and QCISD levels, as well as those obtained by the B3LYP density functional method. We have also found that the values of the rotational constants are a tight criterion to define the quality of a molecular geometry. \u00a9 1995 by John Wiley &amp; Sons, Inc.<\/jats:p>","DOI":"10.1002\/jcc.540160302","type":"journal-article","created":{"date-parts":[[2005,1,2]],"date-time":"2005-01-02T01:08:25Z","timestamp":1104628105000},"page":"263-272","source":"Crossref","is-referenced-by-count":84,"title":["The geometry of pyrazole: A test for <i>ab initio<\/i> calculations"],"prefix":"10.1002","volume":"16","author":[{"given":"Antonio L.","family":"Llamas\u2010Saiz","sequence":"first","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Concepci\u00f3n","family":"Foces\u2010Foces","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Otilia","family":"M\u00f3","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Manuel","family":"Y\u00e1\u00f1ez","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Eric","family":"Elguero","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jos\u00e9","family":"Elguero","sequence":"additional","affiliation":[],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"311","published-online":{"date-parts":[[2004,9,7]]},"reference":[{"key":"e_1_2_1_2_2","doi-asserted-by":"publisher","DOI":"10.1016\/0022-2860(93)07935-P"},{"key":"e_1_2_1_3_2","first-page":"137","volume-title":"Ab Initio Molecular Orbital Theory","author":"Hehre W. 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