A factor introduced into simple versions of the
collision theory of reactions to take care of the fact that the
reaction probability depends on the certain mutual orientations of the reactant molecules.
Source:
PAC, 1996, 68, 149
(A glossary of terms used in chemical kinetics, including reaction dynamics (IUPAC
Recommendations 1996))
on page 187
See also:
PAC, 1990, 62, 2167
(Glossary of atmospheric chemistry terms (Recommendations 1990))
on page 2216