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

Compare vibrational frequencies for two calculations for CHONH2 (formamide)

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'   3570 3562 7.2 1.002   1.106 1.106 0.000 1.000   63.50 55.54 7.96 1.143
2 A' A'   3449 3428 20.3 1.006   1.047 1.046 0.001 1.001   57.94 56.98 0.96 1.017
3 A' A'   2888 2876 12.4 1.004   1.089 1.088 0.001 1.001   103.77 100.39 3.37 1.034
4 A' A'   1796 1733 62.9 1.036   7.285 6.846 0.439 1.064   514.88 332.00 182.88 1.551
5 A' A'   1607 1559 48.8 1.031   1.220 1.251 -0.031 0.975   83.94 66.02 17.92 1.271
6 A' A'   1405 1372 32.7 1.024   1.223 1.203 0.020 1.016   10.34 4.54 5.80 2.280
7 A' A'   1239 1234 4.6 1.004   2.675 2.849 -0.174 0.939   155.14 100.12 55.02 1.550
8 A' A'   1042 1011 31.0 1.031   1.782 1.741 0.041 1.023   8.36 3.88 4.48 2.155
9 A' A'   555 534 21.1 1.040   2.501 2.463 0.038 1.015   17.29 11.39 5.90 1.518
10 A" A"   1063 995 67.7 1.068   1.568 1.526 0.043 1.028   2.51 0.79 1.72 3.162
11 A" A"   605 615 -10.3 0.983   1.196 1.207 -0.010 0.991   32.52 20.64 11.87 1.575
12 A" A"   97 129i 226.4 -0.754   1.221 1.231 -0.010 0.992   334.98 301.66 33.32 1.110
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.