OVERALL ROTATION ALONG A REACTION-PATH

It is shown that, along a reaction path defined as a line in an atomic Cartesian component configuration space (whatever the actual definiti on of this line, provided that it joins continuously the reagent and t he product representative points through all intermediate stationary p oints), overall (i.e. tumbling) rotation of the body-fixed frame of re ference linked with the molecular system (the only relevant definition of 'molecular rotation' for a very deformable molecular system) neces sarily takes place, a point generally overlooked and even sometimes de nied.