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

Compare vibrational frequencies for two calculations for CH3CHN (methylmethaniminyl radical)

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'   2972 3058 -85.7 0.972   1.103 1.105 -0.002 0.998   17.10 4.08 13.02 4.194
2 A' A'   2912 2946 -33.7 0.989   1.082 1.035 0.047 1.045   17.14 4.44 12.70 3.857
3 A' A'   2885 2909 -23.9 0.992   1.037 1.085 -0.048 0.956   20.47 17.66 2.82 1.159
4 A' A'   1506 2002 -496.1 0.752   2.471 10.521 -8.050 0.235   7.88 65.22 -57.34 0.121
5 A' A'   1446 1454 -7.8 0.995   1.311 1.045 0.266 1.255   2.31 12.22 -9.91 0.189
6 A' A'   1393 1368 24.8 1.018   1.256 1.242 0.013 1.011   2.53 5.84 -3.31 0.433
7 A' A'   1219 1237 -18.2 0.985   1.297 1.161 0.136 1.117   3.07 3.23 -0.17 0.948
8 A' A'   1050 1045 5.5 1.005   1.837 2.073 -0.236 0.886   13.14 11.59 1.54 1.133
9 A' A'   876 904 -28.1 0.969   2.252 1.888 0.364 1.193   2.22 1.38 0.84 1.611
10 A' A'   426 424 1.7 1.004   3.365 3.441 -0.076 0.978   20.31 21.81 -1.50 0.931
11 A" A"   2938 3029 -90.9 0.970   1.102 1.103 -0.001 0.999   22.74 5.99 16.74 3.795
12 A" A"   1458 1455 2.7 1.002   1.046 1.046 -0.001 0.999   7.65 11.02 -3.37 0.694
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.