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Compare vibrational frequencies for two calculations for CH2CHCONH2 (Acrylamide)


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

scale factors=0.8985, 0.943 0.516 -0.238 -0.109 0.137
  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 3540 30.1 1.008   1.106 1.104 0.002 1.002   54.54 43.21 1.262
2 A A   3453 3413 40.4 1.012   1.047 1.046 0.001 1.001   67.26 59.65 1.128
3 A A   3094 3134 -40.1 0.987   1.118 1.118 -0.001 0.999   3.80 2.28 1.667
4 A A   3021 3046 -25.4 0.992   1.087 1.084 0.002 1.002   14.59 8.95 1.631
5 A A   3004 3033 -28.9 0.990   1.069 1.068 0.001 1.001   11.93 4.60 2.593
6 A A   1769 1713 56.0 1.033   8.363 7.847 1.066   353.89 213.81 1.655
7 A A   1674 1623 51.2 1.032   4.634 4.872 0.951   59.00 22.82 2.585
8 A A   1616 1570 46.0 1.029   1.226 1.243 -0.017 0.986   150.12 111.82 1.343
9 A A   1423 1400 23.0 1.016   1.360 1.383 -0.023 0.983   109.98 85.59 1.285
10 A A   1329 1312 17.1 1.013   1.870 1.979 0.945   72.88 62.44 1.167
11 A A   1267 1248 19.4 1.016   1.670 1.534 1.089   138.33 69.55 1.989
12 A A   1100 1076 24.3 1.023   1.983 1.955 0.028 1.014   6.25 4.00 1.563
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.