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III.G.7. (XIII.B.3.) (XIII.D.5.)

Compare vibrational frequencies for two calculations for CuCH3 (monomethyl copper)

A = HF/6-31G*

B = MP2FC/6-31G*

  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   2846 2921 -74.7 0.974   1.034 1.033 0.001 1.001   66.07 3.40 62.67 19.418
2 A1 A1   1204 1234 -30.1 0.976   1.237 1.304 -0.067 0.948   62.07 110.54 -48.46 0.562
3 A1 A1   514 683 -168.3 0.754   4.103 3.511 0.591 1.168   44.88 38.79 6.09 1.157
4 E E   2898 3004 -105.7 0.965   1.098 1.100 -0.001 0.999   26.54 1.12 25.42 23.654
5 E E   1425 1391 34.3 1.025   1.061 1.064 -0.003 0.997   2.12 0.47 1.65 4.536
6 E E   602 690 -88.0 0.872   1.172 1.174 -0.002 0.999   120.93 79.48 41.45 1.522
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.