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

Compare vibrational frequencies for two calculations for C6H12 (Cyclobutane, ethyl-)

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   2951 3013 -61.7 0.980   1.108 1.106 0.001 1.001   122.30 38.10 84.20 3.210
2 A A   2935 3011 -75.6 0.975   1.106 1.105 0.001 1.001   55.78 60.49 -4.70 0.922
3 A A   2930 3007 -76.9 0.974   1.106 1.103 0.003 1.002   30.26 22.28 7.98 1.358
4 A A   2928 2994 -65.4 0.978   1.103 1.109 -0.006 0.995   72.35 4.79 67.57 15.109
5 A A   2924 2988 -64.2 0.979   1.108 1.109 -0.002 0.998   8.20 14.92 -6.71 0.550
6 A A   2910 2956 -46.0 0.984   1.068 1.098 -0.030 0.973   7.31 48.10 -40.79 0.152
7 A A   2898 2951 -53.6 0.982   1.072 1.066 0.005 1.005   95.27 9.37 85.90 10.171
8 A A   2893 2939 -46.0 0.984   1.062 1.063 -0.000 1.000   106.30 22.10 84.20 4.810
9 A A   2888 2935 -46.3 0.984   1.079 1.059 0.020 1.019   7.58 56.57 -48.99 0.134
10 A A   2877 2926 -48.2 0.984   1.091 1.045 0.046 1.044   14.23 29.78 -15.56 0.478
11 A A   2874 2924 -49.8 0.983   1.039 1.072 -0.033 0.969   21.81 10.03 11.78 2.175
12 A A   2860 2909 -48.6 0.983   1.061 1.061 -0.000 1.000   31.72 18.41 13.31 1.723
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.