Ab initio quantum mechanical characterization of the low-lying cation doublet states of uracil. Interpretation of uv and x-ray photoelectron spectra

Journal Article · Tue Jan 01 04:00:00 EST 1980 · J. Phys. Chem.; (United States)

DOI:https://doi.org/10.1021/j100452a021· OSTI ID:6775697

O'Donnell, T J ^[1]; LeBreton, P R; Petke, J D; Shipman, L L

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1. Univ. of Illinois, Chicago

Ab initio configuration interaction wave functions have been computed for the ground singlet state and the 10 lowest A' and A'' cation doublet states of uracil. Both the small molecular fragment basis set and a much larger double zeta basis set have been employed. The experimental ordering of the terminus states in the uracil ..-->.. uracil/sup +/ . transitions of the uv photoelectron spectrum is A'', A', A'', A', A'' in order from lowest to higher ionization potentials. The molecular fragment basis set gives the experimental ordering with the Koopmans' theorem approximation but gives an incorrect ordering (A', A'', A' approx. A'', A') when configuration interaction is applied. The double zeta basis set, on the other hand, gives an incorrect ordering with the Koopmans' theorem approximation (A'', A'', A', A', A'') but gives the experimental ordering after configuration interaction is applied. The best of these calculations utilized the double zeta basis set plus configuration interaction; these results lend support to the previously made assignment of the first five bands of the uv photoelectron spectrum. The results of the double zeta calculation have been used to extend the assignment of the uv photoelectron spectrum to A'', A', A'', A', A'', A'', A', A'. The eight inner-shell molecular orbitals and their orbital energies from the double zeta calculation have been used to assign the experimental x-ray photoelectron spectrum of uracil. The following ordering was computed: O/sub 1/ (bonded to C/sub 2/), O/sub 2/ (bonded to C/sub 4/), N/sub 1/, N/sub 3/, C/sub 2/, C/sub 4/, C/sub 6/, C/sub 5/ in order of decreasing ionization potential. 31 references, 6 figures, 9 tables.

• OSTI ID: 6775697
• Journal Information: J. Phys. Chem.; (United States), Journal Name: J. Phys. Chem.; (United States) Vol. 84; ISSN JPCHA
• Country of Publication: United States
• Language: English

Related Subjects

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400104 -- Spectral Procedures-- (-1987)
400301* -- Organic Chemistry-- Chemical & Physicochemical Properties-- (-1987)
AZINES
CONFIGURATION INTERACTION
DATA
ELECTRON SPECTROSCOPY
ELECTRONIC STRUCTURE
ENERGY LEVELS
EXPERIMENTAL DATA
GROUND STATES
HETEROCYCLIC COMPOUNDS
HYDROXY COMPOUNDS
INFORMATION
IONIZATION POTENTIAL
MECHANICS
MOLECULAR STRUCTURE
MULTIPLETS
NUMERICAL DATA
ORGANIC COMPOUNDS
ORGANIC NITROGEN COMPOUNDS
PHOTOELECTRON SPECTROSCOPY
PYRIMIDINES
QUANTUM MECHANICS
SPECTRA
SPECTROSCOPY
STRUCTURAL CHEMICAL ANALYSIS
ULTRAVIOLET SPECTRA
URACILS