Prediction of microwave transitions, torsional energies and transition matrix elements of CHD2OD

Torsional-rotational contributions to the total energy of asymmetrically de uterated methanol CHD,OD have been computed by applying an internal axis me thod (IAM) Hamiltonian. Torsional energy and transition matrix elements for Delta K= +/-1 transitions have thereby been calculated up to the axial tor sional quantum number K=15. Prediction of microwave transitions in the grou nd torsional states (e(0), o(1) and e(1)) have also been reported. These pr edictions are extremely valuable in identifying and measuring unobserved MW transitions. The computed data provide sensitive tests in the assignments of the high resolution far-infrared spectrum and optically pumped far-infra red laser lines in this molecular species. The spectroscopic parameters and predictions will be an useful kit for astrophysical detection of this mole cular species in the interstellar space, which in turn might provide the D/ H ratio. (C) 1999 Elsevier Science B.V. All rights reserved.