{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,5,1]],"date-time":"2026-05-01T22:52:37Z","timestamp":1777675957957,"version":"3.51.4"},"reference-count":28,"publisher":"SAGE Publications","issue":"1","license":[{"start":{"date-parts":[[1994,3,1]],"date-time":"1994-03-01T00:00:00Z","timestamp":762480000000},"content-version":"tdm","delay-in-days":0,"URL":"https:\/\/journals.sagepub.com\/page\/policies\/text-and-data-mining-license"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["The International Journal of Supercomputer Applications and High Performance Computing"],"published-print":{"date-parts":[[1994,3]]},"abstract":"<jats:p>An MM2 force field that reproduces the structural fea tures and relative energies of quaternary aliphatic amines as derived from ab initio calculations at the 6-31G* level has been completed. The purpose of the study is to provide Medicinal Chemists with a method of evaluating the structures and conformational ener gies of ammonium species typically found in pharma ceuticals. Full Cartesian coordinate geometry optimiza tions at the 6-31G* level are followed by single-point M\u00f8ller-Plesset Perturbation calculations through the MP3 level, which were performed on CRAY X-MP\/4, CRAY Y-MP\/464, and VAX 8800 machines using Gaus sian 80(UCSF). Methyl-, ethyl-, propyl-, and ethylmethyl- amines, N-Methylpiperidine, 2-Methylpiperidine, and corresponding ammonium systems are used to evalu ate changes in structure, barrier heights, and relative energies resulting from quaternization.<\/jats:p>","DOI":"10.1177\/109434209400800105","type":"journal-article","created":{"date-parts":[[2007,3,11]],"date-time":"2007-03-11T03:54:27Z","timestamp":1173585267000},"page":"35-46","source":"Crossref","is-referenced-by-count":1,"title":["Relative Energies and Structural Features of Small Amines and Their Ammonium Analogs: Results From 6-31G* Optimizations and an Mm2 Ammonium Force Field"],"prefix":"10.1177","volume":"8","author":[{"suffix":"JR","given":"Salvatore","family":"Profeta","sequence":"first","affiliation":[{"name":"DEPARTMENT OF RESEARCH COMPUTING GLAXO INC. RESEARCH\rINSTITUTE RESEARCH TRIANGLE PARK, NORTH CAROLINA 27709"}]},{"given":"Rayomand J.","family":"Unwalla","sequence":"additional","affiliation":[{"name":"DEPARTMENT OF RESEARCH COMPUTING GLAXO INC. RESEARCH\rINSTITUTE RESEARCH TRIANGLE PARK, NORTH CAROLINA 27709"}]},{"given":"Daniel J.","family":"Russell","sequence":"additional","affiliation":[{"name":"DEPARTMENT OF RESEARCH COMPUTING GLAXO INC. RESEARCH\rINSTITUTE RESEARCH TRIANGLE PARK, NORTH CAROLINA 27709"}]}],"member":"179","published-online":{"date-parts":[[1994,3,1]]},"reference":[{"key":"atypb1","doi-asserted-by":"publisher","DOI":"10.1002\/jcc.540060304"},{"key":"atypb2","doi-asserted-by":"publisher","DOI":"10.1007\/BF00124339"},{"key":"atypb3","first-page":"S1","author":"Allen, F.H.","year":"1987","journal-title":"J. Chem. Soc. 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