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Compare vibrational frequencies for two calculations for CHONH2 (formamide)


A = HF/6-31G*
B = MP2/6-31G*

scale factors=0.8985, 0.943 0.439 -0.174
  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 1.143
2 A' A'   3449 3428 20.3 1.006   1.047 1.046 0.001 1.001   57.94 56.98 1.017
3 A' A'   2888 2876 12.4 1.004   1.089 1.088 0.001 1.001   103.77 100.39 1.034
4 A' A'   1796 1733 62.9 1.036   7.285 6.846 1.064   514.88 332.00 1.551
5 A' A'   1607 1559 48.8 1.031   1.220 1.251 -0.031 0.975   83.94 66.02 1.271
6 A' A'   1405 1372 32.7 1.024   1.223 1.203 0.020 1.016   10.34 4.54 2.280
7 A' A'   1239 1234 4.6 1.004   2.675 2.849 0.939   155.14 100.12 1.550
8 A' A'   1042 1011 31.0 1.031   1.782 1.741 0.041 1.023   8.36 3.88 2.155
9 A' A'   555 534 21.1 1.040   2.501 2.463 0.038 1.015   17.29 11.39 1.518
10 A" A"   1063 995 67.7 1.068   1.568 1.526 0.043 1.028   2.51 0.79 3.162
11 A" A"   605 615 -10.3 0.983   1.196 1.207 -0.010 0.991   32.52 20.64 1.575
12 A" A"   97 129i 226.4 -0.754   1.221 1.231 -0.010 0.992   334.98 301.66 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.