l-Dominant study of rotationally inelastic Li$sup +$--H$sub 2$ collisions
For rotationally inelastic collisions at large total angular momentum J, the orbital angular momentum l exerts considerable dynamical importance. The inelastic T matrix is dominated by transitions between states characterized by small centrifugal barriers. Recognizing this fact, we have recently developed an ''l-dominant'' (LD) approximation to the space-fixed quantum-mechanical close- coupled (CC) equations, which consists in neglecting all channels with l>J. In the present work we have applied the LD method to the determination of partial and total cross sections for the j=0$Yields$2,4,6 processes in Li$sup +$--H$sub 2$ collisions at an energy of 0.5 eV. For the 0$Yields$2 and 0$Yields$4 transitions the LD results agree well with exact CC values, particularly at high J where the l dominance is most pronounced. By contrast, agreement is less satisfactory for the weak 0$Yields$6 transition, where high J values do not contribute significantly to the total cross section. Compared with the results of coupled-states (CS) calculations, the LD partial cross sections are considerably more accurate. In terms of computational expense, the LD method lies midway between CS and CC calculations. (AIP)
- Research Organization:
- Department of Chemistry, University of Maryland, College Park, Maryland 20742
- NSA Number:
- NSA-33-015666
- OSTI ID:
- 4084273
- Journal Information:
- J. Chem. Phys., v. 63, no. 12, pp. 5327-5332, Other Information: Orig. Receipt Date: 30-JUN-76
- Country of Publication:
- United States
- Language:
- English
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