Unlike the N-H bond length, the C=O bond length does not change substantially in uracil in methanol. In propanamide in water, the C=O bond is elongated by 0.012 Å. This is in line with the difference in angular deviations of the modes. The lower errors of the C=O stretching modes compared to the N-H stretching suggest a higher sensitivity for hydrogenbond donors than for hydrogen-bond acceptors. In regards to the pseudo-translational and pseudo-rotational contributions, although small, there are visible changes outside of the six lowest frequency modes. For example, for normal mode 30 for uracil in methanol and normal modes 27, 28, 29, and 30 for propanamide in water. Except for normal mode 30 for propanamide in water, all of these modes had no contributions in the partial QM Hessian and, therefore, arose solely from the partial QM/MM Hessian.