Knowledge Bank

A Hamiltonian matrix suitable for fitting rotational energy levels of the hydrazine $molecule1$ $(H2N-NH2)$ in its ground vibrational and electronic state has need obtained. This matrix is, of dimension $16\times 16$, where the 16 functions labeling the rows and columns consist of the two members of a near-prolate asymmetric rotor doublet (with given $|Ka|)$ for the eight different, but chemically equivalent, conformers which the molecule can reach by various combinations of the - $NH2$ inversion at either end of the molecule, and the internal rotation about the N-N bond. The matrix is derived in a phenomenological fashion, by applying group theoretical $arguments2$ to a model in which tunneling among the various frameworks is assumed to be very slow compared with the vibrational frequencies. A comprehensive treatment of the large-amplitude vibrational potential surfaces and associated tunneling pathways has not been carried out, nor have quartic $(J4)$ centrifugal distortion effects been considered in a systematic fashion. Preliminary fits indicate that the model developed can be used to fit the hydrazine microwave $data3$ in a consistent fashion, and a full treatment of such data has been undertaken.