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

Compare vibrational frequencies for two calculations for H2OH2CO (water formaldehyde dimer)

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   3744 3659 84.6 1.023   1.081 1.078 0.003 1.003   118.29 89.60 28.69 1.320
2 A A   3634 3513 121.6 1.035   1.048 1.049 -0.001 0.999   85.36 98.85 -13.49 0.864
3 A A   2947 2970 -23.3 0.992   1.119 1.121 -0.002 0.998   73.03 58.45 14.57 1.249
4 A A   2864 2875 -11.6 0.996   1.053 1.049 0.004 1.004   54.16 54.14 0.02 1.000
5 A A   1803 1663 139.9 1.084   7.074 3.461 3.613 2.044   150.99 29.59 121.40 5.103
6 A A   1659 1659 -0.0 1.000   1.079 1.176 -0.097 0.917   101.81 98.04 3.77 1.038
7 A A   1503 1482 20.8 1.014   1.106 1.205 -0.099 0.918   15.75 10.86 4.89 1.450
8 A A   1247 1226 21.2 1.017   1.338 1.325 0.013 1.010   16.97 4.74 12.23 3.582
9 A A   1212 1157 55.1 1.048   1.363 1.355 0.009 1.006   0.77 4.57 -3.80 0.168
10 A A   471 557 -86.4 0.845   1.056 1.046 0.010 1.010   246.88 247.56 -0.68 0.997
11 A A   274 314 -39.6 0.874   1.103 1.081 0.021 1.020   115.42 86.30 29.12 1.337
12 A A   171 215 -43.9 0.796   1.098 1.084 0.014 1.013   27.62 40.91 -13.29 0.675
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.