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Cyclobutadiene automerization and rotation of ethylene: Energetics of the barriers by using Spin‐polarized wave functions
Author(s) -
SanFabián Emilio,
Moscardó Federico
Publication year - 2014
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.23630
Subject(s) - cyclobutadiene , wave function , basis set , singlet state , spin (aerodynamics) , spin states , chemistry , ground state , gaussian , molecular physics , computational chemistry , physics , atomic physics , quantum mechanics , density functional theory , molecule , thermodynamics , excited state
Spin‐projected spin polarized Møller–Plesset and spin polarized coupled clusters calculations have been made to estimate the cyclobutadiene automerization, the ethylene torsion barriers in their ground state, and the gap between the singlet and triplet states of ethylene. The results have been obtained optimizing the geometries at MP4 and/or CCSD levels, by an extensive Gaussian basis set. A comparative analysis with more complex calculations, up to MP5 and CCSDTQP, together with others from the literature, have also been made, showing the efficacy of using spin‐polarized wave functions as a reference wave function for Møller–Plesset and coupled clusters calculations, in such problems. © 2014 Wiley Periodicals, Inc.