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

Compare vibrational frequencies for two calculations for SO2 (Sulfur dioxide)

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   1221 1016 204.5 1.201   17.980 18.020 -0.040 0.998   63.82 13.12 50.71 4.866
2 A1 A1   532 459 73.6 1.160   18.589 18.546 0.042 1.002   61.77 31.98 29.79 1.932
3 B2 B2   1410 1231 178.5 1.145   20.318 20.350 -0.032 0.998   321.84 79.45 242.39 4.051
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.