Theoretical investigations of rotationally inelastic collisions in the CO/sub 2/+He system using ab initio, electron-gas, and ''experimental'' potential-energy surfaces

Journal Article · Thu May 15 04:00:00 EDT 1980 · J. Chem. Phys.; (United States)

OSTI ID:5319316

Stroud, C L; Raff, L M

The inelastic collision dynamics of the rigid rotor (CO/sub 2/,He) system have been examined on three different potential-energy surfaces, an ab initio SCF surface, an electron-gas surface, and a potential obtained by deconvolution of molecular-beam scattering data. Thermally averaged cross sections, state-to-state integral cross sections, and differential cross sections have been computed on each surface as a function of collision energy and initial CO/sub 2/ rotation state from the results of about 28 500 quasiclassical trajectories. At energies less than the depth of the van der Waals well, the SCF surface is found to be inadequate in that it underestimates the state-to-state cross sections by as much as a factor of 5. However, at collision energies in excess of the well depth, all surfaces are found to yield results whose maximum difference is about 20%. Of the surfaces investigated, the electron-gas model predicts the largest degree of rotational inelasticity. Previously reported computations by Preston and Pack indicate this inelasticity to be too large. The present calculations suggest that this is not directly connected to the magnitude or location of the attractive well but rather to the steepness of the repulsive potential which is largest for the electron-gas surface. Nearly linear surprisal plots are obtained for the SCF and electron-gas surfaces. The surprisal for the ''experimental'' surface is significantly more sigmoid in shape. The shapes of the state-to-state differential cross sections are very similar, and they may be correlated with the magnitude of the integral state-to-state cross sections. In general, it is concluded that except at very low collision energies on the SCF surface, each of the potentials permits reasonably accurate calculations of the properties associated with thermal scattering.

• Research Organization: Department of Chemistry, Oklahoma State University, Stillwater, Oklahoma 74074
• OSTI ID: 5319316
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 72:10; ISSN JCPSA
• Country of Publication: United States
• Language: English

Related Subjects

640304* -- Atomic
Molecular & Chemical Physics-- Collision Phenomena
74 ATOMIC AND MOLECULAR PHYSICS
ATOM COLLISIONS
ATOM-MOLECULE COLLISIONS
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
COLLISIONS
CRYOGENIC FLUIDS
ELEMENTS
ENERGY
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITED STATES
FLUIDS
HELIUM
MOLECULE COLLISIONS
NONMETALS
OXIDES
OXYGEN COMPOUNDS
POTENTIAL ENERGY
RARE GASES
ROTATIONAL STATES