Dimethylamine, double torsion

Let now consider the double methyl torsion in dimethylamine, let us remark that the two methyl groups are superimposable by reflection, see Fig. 

Table 6a. Calculated frequencies (in cm ) and relative intensities for the symmetric u 2 torsion mode (double antigearing rotation) in dimethylamine.

It is easily seen that this three-dimensional Hamiltonian operator is invariant under the same operations that those of the two-dimension ll problem, since the bending mode is totally symmetric. The r-NRG for double methyl torsion and bending in dimethylamine will be the Gig. 

---