Geometry of the n. pi. * states of p-benzoquinone. A comparison of valence-bond and configuration-interaction descriptions
The description of the n..pi..* excited states of p-benzoquinone by a configuration-interaction (CI) expansion based on symmetry-restricted molecular orbitals is compared to a valence-bond (VB) model based on a nonorthogonal two-configuration wave function utilizing broken-symmetry, self-consistent-field solutions. The former approximation is found to converge only very slowly to the latter. The valence-bond model was used to examine the potential energy surface for motion involving the symmetric and antisymmetric combinations of the two carbonyl stretches. The minimum in the symmetric stretch coordinate for both the /sup 3/B/sub 1g/ and /sup 3/A/sub u/ states is substantially longer than the ground-state distance. The surface along the antisymmetric stretch coordinate is very flat, but the calculations find no overwhelming evidence for a global C/sub 2nu/ minimum in the /sup 3/B/sub 1g/ state. 3 figures, 6 tables.
- Research Organization:
- Los Alamos Scientific Lab., NM
- OSTI ID:
- 6732252
- Journal Information:
- J. Phys. Chem.; (United States), Vol. 86:13
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
ORGANIC
PHYSICAL AND ANALYTICAL CHEMISTRY
BENZOQUINONES
STRUCTURAL CHEMICAL ANALYSIS
ATOMIC MODELS
CONFIGURATION INTERACTION
COORDINATION VALENCES
DIMERS
ELECTRONIC STRUCTURE
ENERGY-LEVEL TRANSITIONS
EXCITED STATES
MATHEMATICAL MODELS
MOLECULAR ORBITAL METHOD
MOLECULES
NUMERICAL ANALYSIS
POTENTIAL ENERGY
VALENCE
AROMATICS
ENERGY
ENERGY LEVELS
MATHEMATICS
ORGANIC COMPOUNDS
ORGANIC OXYGEN COMPOUNDS
QUINONES
400301* - Organic Chemistry- Chemical & Physicochemical Properties- (-1987)