Potential energy surfaces governing chemical reactions involving carbon, oxygen, and hydrogen
Lowest singlet states of 0[sub 3] are studied in Full Optimized Reaction Space (FORS) MCSCF level of theory. The ground state potential energy surface contains two minima. Upper min lies 29.8 kcal/mole above ground state min and above the 0[sub 2]([sup 3][Sigma][sub g][sup [minus]]) + 0([sup 3]P) dissociation limit. It resembles a ring structure having D[sub 3h] symmetry. The potential energy surface governing the restricted ring opening of the cyclic 0[sub 3] to the ground state is also computed. A conical intersection is found between potential energy surfaces. This intersection of two states of same symmetry in a real system is proved by the wavefunction sign on a closed loop. Ab-initio calculations on the structure, ring opening and dissociation process of the cyclic C0[sub 2] are reported. Optimal isosceles-triangle geometries corresponding to constraint dissociation OCO [yields] C + 0[sub 2] are determined. The entire surface is computed, revealing a metastable cyclic carbene-type species with a local minimum 137.6 kcal/mole above linear total minimum. Energies are determined for cross sections with lower symmetry , i.e. asymmetric bond lengths. Extended basis set calculations for key regions of ground state [sup 1]A[sub 1] cyclopropylidene (C[sub 2]v) to allene (D[sub 2d]) ring opening reaction surface are performed within the FORS MCSCF framework. Optimized geometries of reactant, product, transition state and allene isomerization transition state as well as the barrier for the ring opening and the allene isomerization together with overall exothermicity are reported in the MCSCF approximation incorporating FORS spaces ranging from 20 to 1764 configurations. Reaction path from the transition state passes from a point where the two surfaces corresponding to the states intersect each other. Potential energy surface governing the ring opening of cyclopropylidene to allene are explained.
- Research Organization:
- Ames Lab., IA (United States)
- Sponsoring Organization:
- DOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- W-7405-ENG-82
- OSTI ID:
- 6793978
- Report Number(s):
- IS-T-1521; ON: DE93006915
- Country of Publication:
- United States
- Language:
- English
Similar Records
Ring opening of cyclopropylidenes to allenes: reactions with bifurcating transition regions, free internal motions, steric hindrances, and long-range dipolar interactions
Description of chemical reactions by the method of the Full Optimized Reaction Space. The ring-opening of unsubstituted and substituted cyclopropylidene to allene
Related Subjects
400201* -- Chemical & Physicochemical Properties
664100 -- Theory of Electronic Structure of Atoms & Molecules-- (1992-)
74 ATOMIC AND MOLECULAR PHYSICS
ALLENE
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
CHEMICAL REACTIONS
DIENES
ELECTRONIC STRUCTURE
ENERGY
ENERGY LEVELS
GROUND STATES
HYDROCARBONS
ISOMERIZATION
ORGANIC COMPOUNDS
OXIDES
OXYGEN COMPOUNDS
OZONE
POLYENES
POTENTIAL ENERGY
SELF-CONSISTENT FIELD
SURFACES