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Compare vibrational frequencies for two calculations for C10H8 (Azulene)


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

scale factors=0.8985, 0.943 -1.670 -0.133 -0.243 0.487
  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 A1 A1   3069 3082 -13.4 0.996   1.103 1.104 -0.001 0.999   27.07 8.50 3.184
2 A1 A1   3043 3059 -15.6 0.995   1.089 1.089 0.000 1.000   10.24 6.43 1.593
3 A1 A1   3028 3036 -7.7 0.997   1.094 1.094 0.000 1.000   39.38 24.50 1.607
4 A1 A1   3004 3008 -3.9 0.999   1.090 1.088 0.003 1.003   11.31 5.47 2.069
5 A1 A1   2992 2992 0.8 1.000   1.085 1.087 -0.002 0.998   0.13 0.44 0.300
6 A1 A1   1604 1578 26.6 1.017   6.539 8.209 0.797   119.37 23.34 5.114
7 A1 A1   1552 1520 32.4 1.021   3.072 3.204 0.959   5.18 5.17 1.001
8 A1 A1   1463 1432 30.9 1.022   2.429 2.672 0.909   38.46 20.42 1.883
9 A1 A1   1401 1375 26.4 1.019   2.784 2.298 1.212   194.18 65.34 2.972
10 A1 A1   1265 1252 12.7 1.010   2.661 2.693 -0.033 0.988   1.29 0.25 5.148
11 A1 A1   1209 1200 9.5 1.008   1.314 1.318 -0.004 0.997   0.00 1.53 0.002
12 A1 A1   1054 1041 12.1 1.012   1.551 1.528 0.023 1.015   4.68 4.39 1.066
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.