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Compare vibrational frequencies for two calculations for C5H8 (Cyclopentene)


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

scale factors=0.8985, 0.943 0.307
  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'   3045 3076 -30.6 0.990   1.105 1.104 0.001 1.001   31.84 20.60 1.546
2 A' A'   2938 3000 -62.1 0.979   1.106 1.107 -0.001 0.999   73.57 35.04 2.099
3 A' A'   2910 2966 -56.1 0.981   1.077 1.096 -0.019 0.983   72.39 30.76 2.353
4 A' A'   2890 2942 -51.8 0.982   1.082 1.065 0.017 1.016   12.63 18.80 0.672
5 A' A'   2864 2908 -43.8 0.985   1.070 1.066 0.004 1.004   36.66 22.06 1.662
6 A' A'   1664 1596 68.1 1.043   5.972 5.665 1.054   1.32 0.70 1.894
7 A' A'   1494 1480 13.9 1.009   1.109 1.110 -0.002 0.998   0.16 0.83 0.187
8 A' A'   1466 1457 8.9 1.006   1.087 1.090 -0.003 0.997   0.68 2.01 0.340
9 A' A'   1329 1294 34.7 1.027   1.655 1.738 -0.083 0.952   0.04 0.67 0.058
10 A' A'   1216 1199 17.0 1.014   1.215 1.232 -0.017 0.987   1.62 1.38 1.178
11 A' A'   1108 1092 16.3 1.015   1.095 1.094 0.000 1.000   0.06 0.16 0.345
12 A' A'   1063 1042 20.6 1.020   1.702 1.708 -0.006 0.997   10.01 5.21 1.922
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.