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

Compare vibrational frequencies for two calculations for ClOO (chloroperoxy radical)

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 A' A'   1714 1630 84.2 1.052   15.996 18.094 -2.097 0.884   33.84 139.43 -105.60 0.243
2 A' A'   642 1030 -388.2 0.623   17.468 17.029 0.439 1.026   18.33 33.36 -15.03 0.549
3 A' A'   431 468 -37.7 0.919   20.379 18.242 2.137 1.117   0.71 3.06 -2.35 0.231
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.