Vibrational relaxation of CO (n=1) in collisions with H2-. I. Potential energy surface and test of dynamical approximations

Zlatko Bacic, R. Schinke, G. H F Diercksen

Research output: Contribution to journalArticle

Abstract

We present a fully quantal dynamical study of vibrational relaxation of CO in collisions with H2 treating H2 as a structureless projectile. The potential energy surface consists of a SCF part, including explicitly the variation with the CO bond distance, and a damped long range dispersion part. This potential model contains only two free parameters in the damping function which have been determined previously by fitting rotationally inelastic beam data for D2-CO. The dynamical calculations are performed within the infinite order sudden approximation (IOSA) and the coupled states approximation (CSA). The IOSA relaxation cross sections are generally a factor of ∼1.5 smaller than the CSA cross sections independent on the initial rotational state of CO for j≲4-6. The relaxation rate constants are very sensitive to small changes of the interaction potential. After readjusting one of the damping parameters (within a range still acceptable with the beam data) the IOSA rate constants agree very well with the experimental ones for ortho H2. It is demonstrated that on the same level of approximation the present rate constants are about three times larger than those obtained from the potential energy surface of Poulsen.

Original languageEnglish (US)
Pages (from-to)236-244
Number of pages9
JournalThe Journal of chemical physics
Volume82
Issue number1
StatePublished - 1985

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Potential energy surfaces
Carbon Monoxide
molecular relaxation
potential energy
Rate constants
collisions
approximation
Damping
Projectiles
damping
cross sections
rotational states
self consistent fields
projectiles

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

Cite this

Vibrational relaxation of CO (n=1) in collisions with H2-. I. Potential energy surface and test of dynamical approximations. / Bacic, Zlatko; Schinke, R.; Diercksen, G. H F.

In: The Journal of chemical physics, Vol. 82, No. 1, 1985, p. 236-244.

Research output: Contribution to journalArticle

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N2 - We present a fully quantal dynamical study of vibrational relaxation of CO in collisions with H2 treating H2 as a structureless projectile. The potential energy surface consists of a SCF part, including explicitly the variation with the CO bond distance, and a damped long range dispersion part. This potential model contains only two free parameters in the damping function which have been determined previously by fitting rotationally inelastic beam data for D2-CO. The dynamical calculations are performed within the infinite order sudden approximation (IOSA) and the coupled states approximation (CSA). The IOSA relaxation cross sections are generally a factor of ∼1.5 smaller than the CSA cross sections independent on the initial rotational state of CO for j≲4-6. The relaxation rate constants are very sensitive to small changes of the interaction potential. After readjusting one of the damping parameters (within a range still acceptable with the beam data) the IOSA rate constants agree very well with the experimental ones for ortho H2. It is demonstrated that on the same level of approximation the present rate constants are about three times larger than those obtained from the potential energy surface of Poulsen.

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