AN INTERNAL AXIS APPROACH FOR THE INTERNAL-ROTATION PROBLEM IN ASYMMETRIC ASYMMETRIC MOLECULES - THEORETICAL FORMULATION

An internal axis (IAM) formulation for internal rotation in molecules has been developed when both the top and frame have planes of symmetry. The rotational coefficients are expanded in Fourier series after the internal axis system has been defined by coordinate transformations. The final form of the Hamiltonian has an extremely clean form which is suitable for computer solution. In the accompanying paper the theory is applied to the analysis of the microwave torsional-rotational spectra of CH2DOH and CHD2OH and then in a second paper to the prediction, assignment, and analysis of the spectrum of CHD2OD. © 1991.