Torsional energies, matrix elements and predictions of microwave transitions in CH2DOD

In this study the torsional-rotational molecular parameters of asymmetrical ly deuterated methanol (CH,DOD) have been calculated up to K = 15 in the to rsional vibrational ground state. Matrix elements for Delta K = +/- 1 trans itions have been calculated up to the fourth excited torsional state. Using previously observed microwave (MW) transitions effective state dependent m olecular parameters have been evaluated for the states involved. These para meters allow the predictions for unobserved microwave transitions to be mad e with a precision which should enable future laboratory and astrophysical detection. The matrix elements and the torsional energies will be valuable in the assignments of far-infrared absorption spectra and optically pumped far-infrared laser lines in this molecular isotopomer of methanol. The ener gy levels calculated will form a useful data-base to aid in the detection o f this isotopic variant of methanol in astrophysical sources which might be of useful for the determination of parameters like the D/H ratio in the un iverse. (C) 1999 Elsevier Science B.V. All rights reserved.