Theoretical studies of the ozone molecule. I. Ab initio MCSCF/CI potential energy surfaces for the X /sup 1/A/sub 1/ and a /sup 2/B/sub 2/ states

Journal Article · Wed Dec 31 23:00:00 EST 1980 · J. Chem. Phys.; (United States)

OSTI ID:7093891

Wilson, Jr, C W; Hopper, D G

The potential energy surfaces for the X /sup 1/A/sub 1/ and first-excited a /sup 3/B/sub 2/ states of ozone are surveyed with accurate ab initio electronic structure calculations. An efficient technique for using the multiconfiguration self-consistent field (MCSCF) method for polyatomics has been established for these computations, and is described in some detail. The method involves a geometry-dependent flow of configurations between the MCSCF wave function and a small configuration interaction (CI) wave function. The configurations are constructed in a set of 8 core, 7 valence, and 4 ''virtual'' MCSCF orbitals, which are expanded in a double-zeta plus polarization one-electron basis. The vertical and adiabatic excitation energies, uncorrected for zero-point energies, are presently obtained as 1.21 and 0.74 eV, respectively. These results are in agreement with other quantitative theoretical studies which are now available for comparison. Furthermore, the present results indicate that O/sub 3/(a /sup 3/B/sub 2/) has an O/sub 2/--O binding energy E/sub b/=0.4 eV and that there is no barrier relative to its adiabatic asymptote, O(/sup 3/P)+O/sub 2/(X /sup 3/..sigma../sup -//sub g/). These energies are estimated to be accurate to within 0.2 eV. Thus, we conclude that O/sub 3/(a /sup 3/B/sub 2/) is a bound state of ozone. Similar MCSCF/CI calculations are reported for the ring state. The implications of this work for ozone chemistry are discussed. The existence of a second bound state, relative to the ground state atom--diatomic asymptote, may have important consequences with regard to the interpretation and modeling of ozone formation from O(/sup 3/P) and O/sub 2/(X /sup 3/..sigma../sup -//sub g/): the a /sup 3/B/sub 2/ state, as well as the X /sup 1/A/sub 1/ state, may be involved.

• Research Organization: Special Projects Division, Science Applications, Inc., La Jolla, California 92038
• OSTI ID: 7093891
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 74:1; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640302* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
74 ATOMIC AND MOLECULAR PHYSICS
CHEMICAL REACTIONS
CONFIGURATION INTERACTION
EARTH ATMOSPHERE
ELECTRONIC STRUCTURE
ENERGY
ENERGY LEVELS
EXCITED STATES
OZONE
PHOTOCHEMICAL REACTIONS
POTENTIAL ENERGY
SELF-CONSISTENT FIELD