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The fixed rotor approximation in the vibronic semi-classical treatment of atom—molecule collisions

✍ Scribed by M. Sizun; D. Grimbert; V. Sidis

Publisher
Elsevier Science
Year
1992
Tongue
English
Weight
367 KB
Volume
195
Category
Article
ISSN
0009-2614

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✦ Synopsis

Calculations for non-adiabatic atom-molecule collisions at low energies frequently make use of a sudden approximation vis-avis the molecule rotation. The present work investigates the effect on vibronic excitation and charge-transfer processes of freeing the rotation of the molecule during the collision. This is achieved in a semi-classical framework. The H+ +02 collisional system is selected for this study in view of the strong anisotropy of the relevant interactions and on account of the availability of fixed rotor data for this system. Results obtained in the 1 eV/amu energy range and higher generally confirm the validity of the fixed rotor approximation.

For this energy range sizeable deviations of free rotor from fixed rotor results appear in exceptional cases for impact parameters of the order of the molecule's bond distance. At lower energies ( d 0.2 eV/amu) the fixed rotor approximation becomes questionable.

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