The ethylenedione anion: Elucidation of the intricate potential energy hypersurface
- Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602 (United States)
- School of Chemistry and Earth Sciences, Northern Territory University, P.O. Box 40146, Casuarina, NT 0811 (Australia)
- Department of Chemistry, University of Alabama at Birmingham, 219-PSB UAB Station, Birmingham, Alabama 35294 (United States)
{ital Ab} {ital initio} molecular orbital theory has been used to study the controversial potential energy surface of the ethylenedione anion C{sub 2}O{sup {minus}}{sub 2}. Seven different basis sets, the largest being triple zeta plus two polarization functions and one set of higher angular momentum functions (TZ2Pf) in quality, were utilized in conjunction with five correlated methods, the highest-level being coupled-cluster theory including single, double, and perturbative triple excitations [CCSD(T)]. Equilibrium geometries and harmonic vibrational frequencies of the predicted {sup 2}{ital A}{sub {ital u}} {ital trans}-bent ground state are presented. The Renner--Teller potential energy surface resulting from the splitting of the doubly degenerate linear {sup 2}{Pi}{sub {ital u}} transition state into the nondegenerate bent {sup 2}{ital A}{sub {ital u}} and linear {sup 2}{ital B}{sub {ital u}} surfaces is also characterized by means of energy predictions for these three states. Several recent peak assignments in the experimental spectrum, as well as the isotopic shifts associated with them, are supported by theory. A correct description of the potential energy hypersurface is obtained only by application of large basis sets in conjunction with methods including high-level treatment of electron correlation effects. The TZP+/CCSD(T) methodology predicts the OCC bond angle to be 146.5{degree}.
- DOE Contract Number:
- FG05-94ER14428
- OSTI ID:
- 29271
- Journal Information:
- Journal of Chemical Physics, Vol. 102, Issue 16; Other Information: PBD: 22 Apr 1995
- Country of Publication:
- United States
- Language:
- English
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