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Compare vibrational frequencies for two calculations for C6H10 (Cyclopentene, 1-methyl-)


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

scale factors=0.8985, 0.943 0.561
  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   3021 3050 -28.5 0.991   1.095 1.094 0.001 1.001   24.69 15.13 1.631
2 A A   2942 3009 -66.7 0.978   1.101 1.103 -0.002 0.999   33.33 17.80 1.873
3 A A   2935 2997 -61.3 0.980   1.106 1.107 -0.001 0.999   73.74 35.24 2.093
4 A A   2907 2979 -72.8 0.976   1.079 1.101 -0.022 0.980   96.44 18.37 5.251
5 A A   2906 2960 -55.0 0.981   1.096 1.096 -0.000 1.000   20.10 30.66 0.656
6 A A   2895 2953 -58.1 0.980   1.093 1.095 -0.002 0.998   43.58 26.83 1.624
7 A A   2885 2939 -54.1 0.982   1.086 1.068 0.018 1.017   14.03 17.02 0.824
8 A A   2866 2911 -45.7 0.984   1.041 1.037 0.004 1.004   57.03 30.90 1.845
9 A A   2861 2904 -43.8 0.985   1.070 1.065 0.005 1.004   70.34 39.88 1.764
10 A A   2856 2899 -42.7 0.985   1.067 1.064 0.003 1.002   40.10 28.37 1.414
11 A A   1699 1636 62.9 1.038   6.883 6.322 1.089   3.09 0.94 3.305
12 A A   1495 1481 14.2 1.010   1.111 1.111 -0.000 1.000   0.18 0.57 0.317
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.