Vibrational relaxation in the para-H/sub 2/--/sup 4/He system: Comparison of coupled-channel, coupled-states, and effective potential methods

Journal Article · Fri Sep 15 04:00:00 EDT 1978 · J. Chem. Phys.; (United States)

OSTI ID:6733653

Raczkowski, A W; Lester, Jr, W A; Miller, W H

Coupled-channel scattering calculations are performed in the energy range of 0.9 to 2.0 eV using both the Gordon--Secrest and the extended Tsapline--Kutzelnigg potentials. Vibrational relaxation rates for p-H/sub 2/--/sup 4/He are computed over the temperature range 50 to 2000 /sup 0/K. Cross sections and relaxation rates are compared to results of coupled-states and effective potential calculations. We find quantitative agreement with coupled-states results and order-of-magnitude agreement with effective potential results. At high temperatures (around 1000 /sup 0/K), relaxation rates computed using coupled-channel cross sections with both the extended TK and GS potentials agree well with experiment. At low temperatures (50 to 500 /sup 0/K), the present CC--GS results lie a factor of 4 above the experimental data, while the CC--TK results are at least a factor of 10 below experiment.

• Research Organization: Department of Chemistry and Materials and Molecular Research Division, Lawrence Berkeley Laboratory, University of California, Berkeley, California 94720
• OSTI ID: 6733653
• Journal Information: J. Chem. Phys.; (United States), Journal Name: J. Chem. Phys.; (United States) Vol. 69:6; 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
COLLISIONS
CRYOGENIC FLUIDS
ELEMENTS
ENERGY LEVELS
ENERGY-LEVEL TRANSITIONS
EXCITED STATES
FLUIDS
HELIUM
HYDROGEN
MOLECULE COLLISIONS
NONMETALS
RARE GASES
RELAXATION
VIBRATIONAL STATES