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

Compare vibrational frequencies for two calculations for OCS+ (Carbonyl sulfide cation)

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 Σ Σ   2122 2942 -820.0 0.721   13.409 13.233 0.176 1.013   209.49 2772.23 -2562.74 0.076
2 Σ Σ   588 644 -56.0 0.913   19.038 19.405 -0.366 0.981   5.89 17.35 -11.46 0.339
3 Π Π   420 412 8.5 1.021   13.028 13.028 -0.000 1.000   20.70 23.00 -2.30 0.900
4 Π Π   383 394 -11.1 0.972   13.028 13.028 -0.000 1.000   26.38 9.39 16.98 2.808
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.