Accuracy of the ''decoupled l-dominant'' approximation for atom--molecule scattering

Journal Article · Thu Jul 01 04:00:00 EDT 1976 · J. Chem. Phys.; (United States)

DOI:https://doi.org/10.1063/1.432756· OSTI ID:7187301

Green, S

Cross sections for rotational excitation and spectral pressure broadening of HD, HCl, CO, and HCN due to collisions with low energy He atoms have been computed within the ''decoupled l-dominant'' (DLD) approximation recently suggested by DePristo and Alexander. These are compared with accurate close coupling results and also with two similar approximations, the effective potential of Rabitz and the coupled states of McGuire and Kouri. These collision systems are all dominated by short-range repulsive interactions although they have varying degrees of anisotropy and inelasticity. The coupled states method is expected to be valid for such systems, but they should be a severe test to the DLD approximation which is expected to be better for long-range interactions. Nonetheless, DLD predictions of state-to-state cross sections are rather good, being only slightly less accurate than coupled states results. DLD is far superior to either the coupled states or effective potential methods for pressure broadening calculations, although it may not be uniformly of the quantitative accuracy desirable for obtaining intermolecular potentials from experimental data. (AIP)

• Research Organization: Goddard Institute for Space Studies, New York, New York 10025
• OSTI ID: 7187301
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 65:1; 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 MONOXIDE
CARBON OXIDES
CHALCOGENIDES
COLLISIONS
CROSS SECTIONS
CRYOGENIC FLUIDS
DECOUPLING
ELEMENTS
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITATION
EXCITED STATES
FLUIDS
HELIUM
HYDROCHLORIC ACID
HYDROCYANIC ACID
HYDROGEN COMPOUNDS
HYDROGEN ISOTOPES
INORGANIC ACIDS
MOLECULE COLLISIONS
NONMETALS
OXIDES
OXYGEN COMPOUNDS
RARE GASES
ROTATIONAL STATES