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

Compare vibrational frequencies for two calculations for N2O+ (Nitrous oxide cation)

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 Σ Σ   1923 3102 -1179.9 0.620   14.003 14.009 -0.005 1.000   1.06 56.86 -55.79 0.019
2 Σ Σ   938 900 37.7 1.042   15.208 15.202 0.006 1.000   1.87 2.19 -0.31 0.856
3 Π Π   457 607 -149.2 0.754   14.236 14.234 0.002 1.000   3.58 1.73 1.85 2.071
4 Π Π   378 471 -92.7 0.803   14.236 14.234 0.002 1.000   4.53 2.21 2.32 2.050
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.