Symmetry of torsional motion of identical tops in the CH2D-CH2D isotopic form of the ethane molecule

The symmetry of the torsional motion of identical tops in the CH2D-CH2D isotopical form of the ethane molecule is described by using the dynamic noninvariant group, i.e., the group that is larger than the symmetry group of the Hamiltonian of intramolecular motion in the Born-Oppenheimer approximation. As a result, the nuclear statistical weights of stationary states are determined with allowance for the motion of identical tops between energetically nonequivalent configurations and a procedure is developed for the qualitative construction of the operators of physical quantities describing the torsional-rotational spectrum of this system in an arbitrary vibronic state.