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Compare vibrational frequencies for two calculations for C5H8O2 (Acetylacetone)


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

scale factors=0.8985, 0.943 1.317 -0.229 0.135
  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   2990 3052 -62.3 0.980   1.104 1.105 -0.001 0.999   10.16 4.67 2.176
2 A A   2942 3007 -65.2 0.978   1.099 1.100 -0.002 0.998   13.99 3.09 4.523
3 A A   2923 2957 -33.9 0.989   1.059 1.058 0.001 1.001   5.12 1.43 3.585
4 A A   2885 2929 -44.0 0.985   1.040 1.036 0.004 1.004   1.12 0.20 5.723
5 A A   1818 1687 131.5 1.078   10.404 9.087 1.145   35.93 10.42 3.447
6 A A   1460 1448 11.6 1.008   1.098 1.072 0.026 1.024   10.33 0.06 187.461
7 A A   1454 1446 7.5 1.005   1.053 1.053 -0.000 1.000   12.98 23.37 0.555
8 A A   1445 1433 11.7 1.008   1.055 1.092 -0.038 0.965   3.52 9.87 0.356
9 A A   1394 1362 32.0 1.024   1.355 1.371 -0.016 0.989   4.82 9.02 0.534
10 A A   1252 1240 11.6 1.009   1.870 2.099 0.891   30.02 25.23 1.190
11 A A   1131 1109 22.4 1.020   1.413 1.345 0.068 1.050   1.31 1.41 0.923
12 A A   1075 1043 31.8 1.030   2.136 2.002 1.067   0.50 0.37 1.352
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.