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

Compare vibrational frequencies for two calculations for C3H7NO (Propanamide)

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   3562 3537 24.9 1.007   1.105 1.103 0.002 1.002   50.36 39.90 10.47 1.262
2 A A   3447 3411 36.0 1.011   1.047 1.046 0.001 1.001   51.65 43.77 7.88 1.180
3 A A   2971 3043 -72.1 0.976   1.104 1.104 0.000 1.000   32.68 14.83 17.85 2.204
4 A A   2952 3029 -76.6 0.975   1.101 1.103 -0.002 0.998   35.88 17.93 17.95 2.001
5 A A   2904 2965 -61.7 0.979   1.100 1.102 -0.002 0.998   20.16 10.83 9.33 1.861
6 A A   2895 2946 -51.1 0.983   1.041 1.037 0.004 1.004   29.67 17.60 12.07 1.686
7 A A   2874 2919 -45.1 0.985   1.063 1.062 0.001 1.001   28.87 16.20 12.67 1.782
8 A A   1780 1713 66.9 1.039   9.533 8.358 1.175 1.141   382.03 223.63 158.40 1.708
9 A A   1614 1569 45.4 1.029   1.224 1.247 -0.024 0.981   126.75 104.07 22.68 1.218
10 A A   1477 1474 3.2 1.002   1.070 1.055 0.015 1.014   10.18 9.65 0.53 1.055
11 A A   1472 1469 3.1 1.002   1.040 1.041 -0.002 0.998   3.88 5.85 -1.97 0.663
12 A A   1454 1448 5.9 1.004   1.087 1.086 0.000 1.000   3.53 5.56 -2.03 0.635
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.