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

Compare vibrational frequencies for two calculations for HCCCN (Cyanoacetylene)

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   3286 3310 -23.4 0.993   1.174 1.146 0.029 1.025   66.40 78.34 -11.94 0.848
2 Σ Σ   2386 2119 266.4 1.126   10.860 9.254 1.606 1.174   52.33 9.65 42.68 5.423
3 Σ Σ   2146 1935 210.5 1.109   6.113 7.972 -1.859 0.767   3.40 4.99 -1.59 0.681
4 Σ Σ   842 841 1.5 1.002   9.228 9.157 0.072 1.008   0.00 0.37 -0.37 0.002
5 Π Π   764 556 208.6 1.375   1.314 1.558 -0.244 0.843   46.78 42.40 4.37 1.103
6 Π Π   764 556 208.6 1.375   1.314 1.558 -0.244 0.843   46.78 42.40 4.37 1.103
7 Π Π   554 433 121.0 1.279   8.570 3.442 5.128 2.490   10.22 6.63 3.58 1.540
8 Π Π   554 433 121.0 1.279   8.570 3.442 5.128 2.490   10.22 6.63 3.58 1.540
9 Π Π   247 218 28.4 1.130   5.334 7.518 -2.184 0.710   0.44 1.60 -1.16 0.276
10 Π Π   247 218 28.4 1.130   5.334 7.518 -2.184 0.710   0.44 1.60 -1.16 0.276
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.