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

Compare vibrational frequencies for two calculations for HCO- (formyl anion)

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'   1229 1219 10.2 1.008   1.662 1.700 -0.038 0.978   1966.82 1329.79 637.04 1.479
2 A' A'   1307 1291 16.0 1.012   1.238 1.380 -0.141 0.898   31.83 117.73 -85.90 0.270
3 A' A'   1749 1674 75.4 1.045   2.431 1.959 0.472 1.241   287.63 391.70 -104.07 0.734
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.