Vinylidene: Potential energy surface and unimolecular reaction dynamics

Journal Article · Tue May 01 04:00:00 EDT 1984 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.447266· OSTI ID:6572126

Carrington, T Jr; Hubbard, L M; Schaefer, III, H F; Miller, W H

New quantum chemistry calculations (with a triple zeta plus polarization basis set, and a single and double configuration interaction) have been carried out to determine the equilibrium points and the transition state for the vinylidene (H/sub 2/C = C:)..-->..acetylene (HCequivalentCH) isomerization. A classical barrier height (i.e., with no zero point energy effects) of 6.3 kcal/mol is obtained, and application of the Davidson correction for unlinked clusters reduces this to 5.4 kcal/mol. Our best estimate is that the true classical barrier lies in the range 2--4 kcal/mol. The dynamics of the vinylidene/acetylene isomerization is described with the framework of the reaction path Hamiltonian. The lifetime of vinylidene (in its ground vibrational state) with respect to this process is calculated to be 0.24 to 4.6 ps for a classical barrier of 2 to 4 kcal/mol. This lifetime decreases by a factor of approx.2 if one quantum of the CH/sub 2/ scissors mode of vinylidene is excited, but is predicted to increase somewhat if a quantum of the C--C stretch is excited. These results are all consistent with the recent experimental observation of vinylidene via photodetachment of C/sub 2/H/sup -//sub 2/.

• Research Organization: Department of Chemistry and Materials and Molecular Research Division, Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720
• OSTI ID: 6572126
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 80:9; 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
ELECTRONIC STRUCTURE
ENERGY
ISOMERIZATION
POTENTIAL ENERGY
RADICALS
VINYLIDENE RADICALS