NORMAL-COORDINATE ANALYSIS AND CORIOLIS COUPLING-CONSTANTS OF ETHYLENE TYPE MOLECULES, C2X4 (X=F, CL, BR, I)

A complete set of Coriolis coupling constants was calculated for C2F4, C2Cl4, C2Br4 and C2I4 using the formulation of Meal and Polo. The har monic force field required to evaluate the coupling constants was obta ined via the iterative consistency Koptev method. The resulting force field and the Coriolis coupling constants were tested by prediction of experimental vibrational frequencies and application of the sum rules , respectively. The inertia defects for the ground vibrational state w ere also calculated.