Quantum mechanical reactive scattering for three-dimensional atom plus diatom systems. II. Accurate cross sections for H+H/sub 2/

Journal Article · Wed Dec 01 04:00:00 EST 1976 · J. Chem. Phys.; (United States)

OSTI ID:7139292

Schatz, G C; Kuppermann, A

Accurate three-dimensional reactive and nonreactive quantum mechanical cross sections for the H+H/sub 2/ exchange reaction on the Porter--Karplus potential energy surface are presented. Tests of convergence in the calculations indicate an accuracy of better than 5% for most of the results in the energy range considered (0.3 to 0.7 eV). The reactive differential cross sections are exclusively backward peaked, with peak widths increasing monotonically from about 32degree at 0.4 eV to 51degree at 0.7 eV. Nonreactive inelastic differential cross sections show backwards to sidewards peaking, while elastic ones are strongly forward peaked with a nearly monotonic decrease with increasing scattering angle. Some oscillations due to interferences between the direct and exchange amplitudes are obtained in the para-to-para and ortho-to-ortho antisymmetrized cross sections above the effective threshold for reaction. Nonreactive collisions do not show a tendency to satisfy a ''j/sub z/-conserving'' selection rule. The reactive cross sections show significant rotational angular momentum polarization with the m/sub j/=m'/sub j/=0 transition dominating for low reagent rotational quantum number j. In constrast, the degeneracy averaged rotational distributions can be fitted to statistical temperaturelike expressions to a high degree of accuracy. The integral cross sections have an effective threshold total energy of about 0.55 eV, and differences between this quantity and the corresponding 1D and 2D results can largely be interpreted as resulting from bending motions in the transition state. (AIP)

• Research Organization: Arthur Amos Noyes Laboratory of Chemical Physics, California Institute of Technology, Pasadena, California 91125
• OSTI ID: 7139292
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 65:11; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640302* -- Atomic
Molecular & Chemical Physics-- Atomic & Molecular Properties & Theory
640304 -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ATOM COLLISIONS
ATOM-MOLECULE COLLISIONS
CHEMICAL REACTION KINETICS
COLLISIONS
CRYOGENIC FLUIDS
DIFFERENTIAL EQUATIONS
ELASTIC SCATTERING
ELEMENTS
EQUATIONS
FLUIDS
HYDROGEN
INELASTIC SCATTERING
KINETICS
MOLECULE COLLISIONS
NONMETALS
REACTION KINETICS
SCATTERING
SCHROEDINGER EQUATION
THREE-DIMENSIONAL CALCULATIONS
WAVE EQUATIONS