THE INVERSION-TORSION POTENTIAL FUNCTION FOR HYDRAZINE

The torsion-inversion potential surface for hydrazine has been determi ned from the rovibrational data using a new rotation-torsion-inversion Hamiltonian. All elements of the inverse moment of inertia tensor hav e been expanded into mixed Fourier series of large amplitude coordinat es. That gives two major advantages: (i) no numerical integration is n ecessary al any step of calculation, and (ii) the three-dimensional in tegrals have been replaced by the products of one-dimensional integral s. It has been proven that the inversion-torsion coupling in hydrazine is negligible and the inversion-inversion coupling is very strong. Th e barrier to inversion of 2072 cm(-1) is slightly higher than that in ammonia and the barrier to internal rotation of 934 cm(-1) is relative ly high but lower than that determined previously from one-dimensional models. (C) 1997 Academic Press.