ROTATIONAL CONSTANTS AND GEOMETRICAL STRUCTURE OF 1A2 AND 3A2 STATES OF H2CO AND D2CO

Double-minimum potential functions have been determined whose vibrational energy levels agree with those observed for the out-of-plane bending potentials of the 1A2 and 3A2 states of H2CO and D2CO. In the determination of the effective structure for each of these electronic states all geometrical parameters except the out-of-plane bending angle θ were assumed to be rigid during the bending vibration. A probability distribution of θ for each level was obtained from the vibrational wave functions. Effective values of the rigid geometrical parameters were determined by adjusting their values until the rotational constants calculated as expectation values of the reciprocals of inertia agreed with the experimentally known rotational constants. The bond lengths were assumed to be the same for H2CO and D2CO. Thus an effective geometrical structure was determined for each electronic state and a corresponding set of rotational constants was calculated for each vibrational level of the bending potential. For the 1A2 state of H2CO the effective structure is s(CH) = 1.095 A ̊, r(CO) = 1.325 A ̊, and 2β (HCH) = 118°. The bending angle g is specified by a distribution function for each level. © 1969.