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

Compare vibrational frequencies for two calculations for C6H5CHCH2 (Styrene)

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   3072 3120 -47.7 0.985   1.116 1.117 -0.001 0.999   22.25 11.55 10.70 1.926
2 A A   3046 3061 -15.2 0.995   1.098 1.100 -0.001 0.999   11.80 13.25 -1.45 0.890
3 A A   3038 3052 -13.6 0.996   1.095 1.095 0.000 1.000   46.78 26.35 20.43 1.775
4 A A   3028 3045 -16.7 0.995   1.093 1.091 0.002 1.002   34.54 8.14 26.41 4.245
5 A A   3018 3037 -18.8 0.994   1.089 1.083 0.007 1.006   0.79 1.52 -0.73 0.521
6 A A   3012 3034 -22.1 0.993   1.087 1.072 0.015 1.014   10.87 1.26 9.61 8.645
7 A A   3006 3028 -22.4 0.993   1.077 1.087 -0.010 0.991   4.77 7.38 -2.62 0.646
8 A A   2992 3015 -23.3 0.992   1.076 1.084 -0.008 0.993   13.52 11.53 1.99 1.173
9 A A   1678 1617 60.4 1.037   4.231 4.323 -0.092 0.979   7.06 3.35 3.70 2.105
10 A A   1626 1582 43.6 1.028   5.152 5.574 -0.423 0.924   4.36 1.70 2.66 2.564
11 A A   1598 1557 40.6 1.026   4.883 5.308 -0.425 0.920   4.01 2.00 2.02 2.009
12 A A   1502 1467 34.7 1.024   2.164 2.248 -0.084 0.963   15.80 11.51 4.29 1.372
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.