Internal Rotation in Two-Top Molecules. I. A General Theory

The dynamics is developed for internal rotation in two-top molecules where both internal rotors may, or may not, be asymmetric. A framework fixed axis method (FFAM) is used for the formulation. The explicit α1 and α2 dependence of the moments of inertia is obtained for over-all rotation, internal rotations, and coupling between over-all and internal rotations. The Hamiltonian in proper Hermitian form is derived. Inertial parameters and rotational coefficients are calculated for two representative molecules.