The dynamics of interacting molecules involve the translation and simultaneous rotation of each molecule in the ensemble. This means that the frame of reference defined by the principal molecular moments of inertia, frame (1,2,3), is a noninertial frame with respect to the laboratory frame (x, y,z). Furthermore, a rotating frame of reference (1,2,3)′ can be generated from (1,2,3) a by translation for each molecule from the center of mass of the origin of (x, y,z). The equations relating velocities, accelerations, and their derivatives in one of these frames to those of another are described and then used to calculate the cross correlation functions.