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

Compare vibrational frequencies for two calculations for HCN- (Hydrogen cyanide 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 Σ Σ   3309 3745 -435.8 0.884   1.208 4.269 -3.061 0.283   60.81 1.27 59.54 47.891
2 Σ Σ   2191 2789 -598.6 0.785   4.802 1.247 3.555 3.850   11.72 336.76 -325.04 0.035
3 Π Π   797 911 -114.1 0.875   1.346 1.339 0.008 1.006   38.08 36.08 2.00 1.055
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.