(c) 2000-2003 by Akira Miyoshi. All rights reserved.
Reaction Dynamics 2002 - section-3.1 appendix

Coefficients for rotational sum (eq. 3.1.5) for specific cases :

product pair
linear + atom2
non-linear + atom3
linear + linear 4 (2+2)
linear + non-linear 5 (2+3)
non-linear + non-linear 6 (3+3)