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

Compare vibrational frequencies for two calculations for NCN (NCN)

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 Σg Σg   1116 1286 -169.9 0.868   14.003 14.003 0.000 1.000   0.00 0.00 0.00  
2 Σu Σu   1321 926 395.2 1.427   12.538 12.538 0.000 1.000   329.30 601.25 -271.94 0.548
3 Πu Πu   338 473 -134.6 0.715   12.538 12.538 0.000 1.000   13.67 24.22 -10.54 0.565
4 Πu Πu   338 473 -134.6 0.715   12.538 12.538 0.000 1.000   13.67 24.22 -10.54 0.565
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.