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

Compare vibrational frequencies for two calculations for S3- (Sulfur trimer 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   602 544 58.0 1.107   31.972 31.972 0.000 1.000   3.05 0.43 2.62 7.111
2 A1 A1   264 248 16.2 1.065   31.972 31.972 0.000 1.000   4.74 2.39 2.35 1.981
3 B2 B2   691 752 -61.6 0.918   31.972 31.972 0.000 1.000   279.67 25.31 254.37 11.051
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.