Campus Units

Chemistry

Document Type

Article

Publication Version

Published Version

Publication Date

2010

Journal or Book Title

Journal of Chemical Physics

Volume

133

First Page

1

Last Page

13

DOI

10.1063/1.3490480

Abstract

Electronic structure calculations at the CASSCF and UB3LYP levels of theory with the aug-cc-pVDZ basis set were used to characterize structures, vibrational frequencies, and energies for stationary points on the ground state triplet and singlet O2+C2H4potential energy surfaces (PESs). Spin-orbit couplings between the PESs were calculated using state averaged CASSCF wave functions. More accurate energies were obtained for the CASSCF structures with the MRMP2/aug-cc-pVDZ method. An important and necessary aspect of the calculations was the need to use different CASSCF active spaces for the different reaction paths on the investigated PESs. The CASSCF calculations focused on O2+C2H4 addition to form the C2H4O2biradical on the triplet and singlet surfaces, and isomerization reaction paths ensuing from this biradical. The triplet and singlet C2H4O2 biradicals are very similar in structure, primarily differing in their C−C−O−O dihedral angles. The MRMP2 values for the O2+C2H4→C2H4O2 barrier to form the biradical are 33.8 and 6.1 kcal/mol, respectively, for the triplet and singlet surfaces. On the singlet surface,C2H4O2 isomerizes to dioxetane and ethane-peroxide with MRMP2 barriers of 7.8 and 21.3 kcal/mol. A more exhaustive search of reaction paths was made for the singlet surface using the UB3LYP/aug-cc-pVDZ theory. The triplet and singlet surfaces cross between the structures for the O2+C2H4 addition transition states and the biradical intermediates. Trapping in the triplet biradical intermediate, following O32+C2H4 addition, is expected to enhance triplet→singlet intersystem crossing.

Comments

The following article appeared in Journal of Chemical Physics 133 (2010): 184206, doi:10.1063/1.3490480.

Rights

Copyright 2010 American Institute of Physics. This article may be downloaded for personal use only. Any other use requires prior permission of the author and the American Institute of Physics.

Copyright Owner

American Institute of Physics

Language

en

File Format

application/pdf

Included in

Chemistry Commons

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