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

Compare vibrational frequencies for two calculations for H2O2 (Hydrogen peroxide)

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   3676 3525 151.5 1.043   1.070 1.070 0.000 1.000   23.72 10.15 13.57 2.337
2 A A   1469 1380 88.5 1.064   1.095 1.091 0.004 1.004   0.49 0.35 0.14 1.393
3 A A   1034 875 158.5 1.181   14.614 14.098 0.517 1.037   1.87 1.63 0.24 1.148
4 A A   356 318 37.9 1.119   1.083 1.082 0.001 1.001   236.10 228.62 7.48 1.033
5 B B   3678 3527 151.1 1.043   1.067 1.067 0.000 1.000   89.27 51.71 37.56 1.726
6 B B   1341 1247 93.8 1.075   1.106 1.097 0.009 1.008   118.87 139.20 -20.33 0.854
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.