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

Compare vibrational frequencies for two calculations for C5H12S (1-Butanethiol, 2-methyl-)

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   2976 3020 -44.1 0.985   1.103 1.102 0.001 1.001   21.91 27.82 -5.91 0.788
2 A A   2950 3016 -66.1 0.978   1.101 1.102 -0.001 0.999   40.56 17.08 23.48 2.374
3 A A   2939 3009 -69.5 0.977   1.102 1.105 -0.003 0.998   103.78 29.03 74.75 3.575
4 A A   2932 3008 -75.7 0.975   1.102 1.103 -0.001 0.999   72.13 25.28 46.84 2.853
5 A A   2930 3002 -72.3 0.976   1.102 1.103 -0.001 0.999   15.92 19.16 -3.24 0.831
6 A A   2914 2957 -42.8 0.986   1.065 1.103 -0.039 0.965   24.58 18.95 5.63 1.297
7 A A   2897 2940 -43.7 0.985   1.100 1.062 0.038 1.035   15.97 21.31 -5.34 0.750
8 A A   2879 2928 -49.1 0.983   1.042 1.037 0.005 1.005   9.41 18.73 -9.32 0.502
9 A A   2878 2922 -44.1 0.985   1.044 1.038 0.006 1.006   71.35 21.95 49.40 3.251
10 A A   2872 2912 -39.9 0.986   1.076 1.072 0.004 1.004   6.38 16.36 -9.98 0.390
11 A A   2864 2906 -42.3 0.985   1.065 1.072 -0.007 0.994   13.05 6.30 6.75 2.071
12 A A   2616 2625 -9.4 0.996   1.039 1.039 0.000 1.000   27.68 18.14 9.54 1.526
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.