Internal Rotation Barriers for Hydrazine and Hydroxylamine from Ab Initio LCAO—MO—SCF Wavefunctions

Abstract

LCAO—MO—SCF ab initio wavefunctions with atomic basis orbitals of double‐zeta accuracy have been constructed for N₂H₄ and NH₂OH and the potential‐energy curves versus internal‐rotation angle have been determined. Similar wavefunctions for CH₃CH₃, CH₃OH, CH₃NH₂, and H₂O₂, reported previously, showed a quantitatively useful correlation with experimental barrier heights and shapes. Since experimental information on the N₂H₄ and NH₂OH barriers is incomplete or unknown, the theoretical results presented here may help guide experimental work. Decomposition of the total energy into one‐ and two‐electron components has been found previously to help elucidate the physical origin of the rotational barrier, and results for the species studied here are given. The wavefunctions presented here (and those reported previously for the species noted above) are the most accurate available for molecules possessing a rotational barrier about a single bond, and comparison is made with the results of the other existing ab initio wavefunctions.