Premium
Isomers of C 20 : An energy profile
Author(s) -
Greene Katherine R.,
Beran Kyle A.
Publication year - 2002
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.10096
Subject(s) - cartesian coordinate system , ring (chemistry) , saddle point , potential energy surface , potential energy , structural isomer , maxima and minima , energy profile , chemistry , surface (topology) , energy (signal processing) , geometry , energy minimization , transformation (genetics) , computational chemistry , physics , atomic physics , stereochemistry , mathematics , molecule , mathematical analysis , quantum mechanics , biochemistry , organic chemistry , gene
Semiempirical calucaltions, at the PM 3 level, are used to geometrically optimize and determine the absolute energies (heats of formation) of a variety of C 20 isomers. Based on the geometrically optimized Cartesian coordinates of the ring and the bowl isomers, and the subsequent saddle‐point calculation, a two‐dimensional energy profile between these two isomers is generated. Performing geometry optimization on the Cartesian coordinates that correspond to energy minima within the ring–bowl profile, we have been able to identify several more isomers of C 20 that are predicted to be energitically stable. With these additional stable structures, we have identified pairs of isomers that lie adjacent to one another on the potential energy surface, as is evidenced by the form of their respective energy profiles. These adjacent pairs of isomers establish a step‐wise transformation between the ring and the bowl. This process, which extends out over the three‐dimensional surface, is predicted to require less energy than that of the direct, two‐dimensional transformation predicted in the ring–bowl profile. © 2002 Wiley Periodicals, Inc. J Comput Chem 23: 938–942, 2002