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

Compare vibrational frequencies for two calculations for MgOH (magnesium hydroxide)

A = HF/6-31G*

B = MP2/6-31G*

scale factors=0.8985, 0.943
  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'   3836 3703 133.2 1.036   1.070 1.069 0.001 1.001   76.84 60.57 16.27 1.269
2 A' A'   715 711 4.0 1.006   10.327 7.272 3.055 1.420   96.15 42.90 53.25 2.241
3 A' A'   76 244 -167.6 0.312   1.166 1.212 -0.046 0.962   199.29 157.91 41.38 1.262
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.