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

Compare vibrational frequencies for two calculations for C2H4CO3 (Ethylene carbonate)

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 A1 A1   2927 2952 -24.6 0.992   1.060 1.059 0.001 1.001   60.16 46.63 13.53 1.290
2 A1 A1   1910 1830 79.9 1.044   12.976 12.994 -0.018 0.999   822.50 520.18 302.32 1.581
3 A1 A1   1535 1518 16.5 1.011   1.095 1.087 0.008 1.007   8.21 3.59 4.62 2.288
4 A1 A1   1397 1352 45.8 1.034   1.406 1.328 0.078 1.059   7.03 1.39 5.63 5.046
5 A1 A1   1232 1155 77.3 1.067   7.788 9.705 -1.917 0.803   317.84 234.37 83.47 1.356
6 A1 A1   922 930 -7.9 0.991   2.865 3.050 -0.184 0.940   16.43 13.57 2.86 1.211
7 A1 A1   835 783 51.4 1.066   10.417 10.673 -0.257 0.976   32.95 40.07 -7.12 0.822
8 A1 A1   711 682 28.6 1.042   12.169 12.234 -0.066 0.995   1.70 0.07 1.63 23.158
9 A2 A2   2947 2991 -43.8 0.985   1.113 1.113 -0.000 1.000   0.00 0.00 0.00  
10 A2 A2   1240 1209 31.2 1.026   1.042 1.051 -0.009 0.992   0.00 0.00 0.00  
11 A2 A2   1161 1133 28.1 1.025   1.631 1.606 0.025 1.016   0.00 0.00 0.00  
12 A2 A2   167i 187i 20.4 0.891   2.204 2.197 0.007 1.003   0.00 0.00 0.00  
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.