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

Compare vibrational frequencies for two calculations for C6H5 (phenyl)

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   3042 3083 -40.4 0.987   1.096 1.098 -0.002 0.998   6.71 0.47 6.24 14.384
2 A1 A1   3031 3077 -46.4 0.985   1.091 1.097 -0.006 0.995   28.64 10.08 18.55 2.840
3 A1 A1   3013 3050 -36.7 0.988   1.087 1.086 0.000 1.000   0.08 0.49 -0.42 0.153
4 A1 A1   1473 1731 -258.5 0.851   2.884 7.506 -4.622 0.384   0.69 2.37 -1.69 0.290
5 A1 A1   1422 1503 -81.7 0.946   1.975 2.572 -0.597 0.768   8.16 15.22 -7.07 0.536
6 A1 A1   1109 1183 -74.4 0.937   1.293 1.080 0.213 1.197   0.04 0.04 -0.01 0.861
7 A1 A1   978 1078 -99.8 0.907   2.530 1.466 1.064 1.726   1.47 16.21 -14.74 0.091
8 A1 A1   953 1024 -71.5 0.930   3.902 6.303 -2.402 0.619   2.16 0.02 2.14 107.383
9 A1 A1   889 933 -43.7 0.953   6.656 7.262 -0.607 0.916   0.18 0.60 -0.41 0.307
10 A1 A1   575 620 -45.2 0.927   7.118 6.721 0.397 1.059   0.74 1.81 -1.07 0.411
11 A2 A2   899 1040 -140.4 0.865   1.360 1.349 0.011 1.008   0.00 0.00 0.00  
12 A2 A2   764 919 -155.5 0.831   1.254 1.248 0.006 1.004   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.