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Compare vibrational frequencies for two calculations for C5H8 (2,3-Pentadiene)


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

scale factors=0.8985, 0.943 0.177 0.805 0.194 -9.027 0.619 0.427
  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   2984 3027 -43.2 0.986   1.089 1.102 -0.013 0.988   19.63 30.10 0.652
2 A A   2955 3027 -71.6 0.976   1.101 1.102 -0.001 0.999   8.30 10.30 0.806
3 A A   2918 3008 -90.6 0.970   1.102 1.090 0.012 1.011   38.87 3.29 11.799
4 A A   2875 3008 -133.5 0.956   1.038 1.090 -0.052 0.952   10.23 3.62 2.829
5 A A   1489 2994 -1504.8 0.497   1.280 1.103 1.161   2.38 18.82 0.126
6 A A   1464 2993 -1529.8 0.489   1.046 1.103 -0.057 0.948   4.12 18.63 0.221
7 A A   1433 2923 -1489.6 0.490   1.841 1.036 1.777   0.00 7.26 0.000
8 A A   1401 2922 -1521.2 0.479   1.230 1.036 1.188   0.57 50.31 0.011
9 A A   1128 1959 -831.0 0.576   1.506 10.533 0.143   0.15 3.10 0.048
10 A A   1076 1478 -401.8 0.728   1.758 1.140 1.543   2.45 2.56 0.954
11 A A   1054 1469 -415.0 0.717   1.470 1.044 1.409   1.34 6.57 0.204
12 A A   901 1459 -558.4 0.617   1.107 1.047 0.060 1.057   21.02 5.21 4.036
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.