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

Compare vibrational frequencies for two calculations for NCO- (cyanate)

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   2185 2366 -180.8 0.924   12.653 12.997 -0.344 0.974   755.66 1008.10 -252.44 0.750
2 Σ Σ   1264 1238 26.0 1.021   14.860 14.515 0.346 1.024   1.28 1.23 0.05 1.041
3 Π Π   632 569 63.2 1.111   12.696 12.715 -0.020 0.998   37.10 20.28 16.82 1.830
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.