This is a comparison of the computed overall structure, left for Kimball.exe, right for G94W RHF/6-31G, starting from the Kimball structure, but optimized. The vibrational analysis produces a stable stationary state.
The overall geometry does not change much between Kimball and optimized
RHF/6-31g. However, there are many changes in bond lengths. Their main
characteristics is the exaggerated difference in the lengths of the formal
N-O and N=O bonds with Kimball. Since Kimball does not allow partial double
bonds, that is what creates the differences in length groups 6-8, 9-11,
and 12-14. The yellow triangles are differences between optimized Sto-3G
and 6-31G. For two out of the three NO-bonds Sto-3G comes out worse than
Kimball in comparison to 6-31G! This is also demonstrated with the energetics
(lower left corner), where the difference in total energy between Sto-3G
and 6-31G is four times larger than that between Kimball and 6-31G.