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

Compare vibrational frequencies for two calculations for CCl2 (dichloromethylene)

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 A1 A1   712 726 -13.9 0.981   14.292 14.208 0.084 1.006   48.84 42.70 6.14 1.144
2 A1 A1   330 334 -4.1 0.988   29.461 29.823 -0.362 0.988   0.02 0.27 -0.24 0.076
3 B2 B2   760 747 13.2 1.018   13.847 13.854 -0.007 0.999   427.87 469.89 -42.02 0.911
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.