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

Compare vibrational frequencies for two calculations for CCl2- (dichloromethylene anion)

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   730 761 -31.4 0.959   17.030 17.116 -0.086 0.995   13.39 4.30 9.09 3.112
2 A1 A1   330 350 -20.1 0.943   22.127 21.984 0.143 1.007   1.83 0.31 1.53 5.974
3 B2 B2   1145 1218 -73.3 0.940   13.480 13.481 -0.001 1.000   592.38 576.50 15.88 1.028
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.