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III.G.7. (XIII.B.3.) (XIII.D.5.)

Compare vibrational frequencies for two calculations for NNH (Dinitrogen monohydride)

A = HF/6-31G*

B = MP2/6-31G*

scale factors=0.8985, 0.943
  symmetry   frequency (cm-1)   reduced mass (amu)   IR Intensity (km mol-1)
mode number A B   A B diff. ratio   A B diff. ratio   A B diff. ratio
1 A' A'   2940 2806 133.9 1.048   1.067 2.308 -1.241 0.462   9.27 107.81 -98.54 0.086
2 A' A'   1494 2667 -1173.1 0.560   8.604 1.725 6.879 4.988   7.74 69.60 -61.86 0.111
3 A' A'   1136 1005 131.5 1.131   1.253 1.220 0.033 1.027   114.88 164.92 -50.05 0.697
scaled by     0.8985 0.943

See section III.C.1 List or set vibrational scaling factors to change the scale factors used here.
See section III.C.2 Calculate a vibrational scaling factor for a given set of molecules to determine the least squares best scaling factor.