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Compare vibrational frequencies for two calculations for NNS (Nitrogen sulfide)


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)   Raman Activity (Å4/u)
mode number A B   A B diff. ratio   A B diff. ratio   A B diff. ratio   A B diff. ratio
1 Σ Σ   2337 1706 630.7 1.370   14.003 14.067 -0.064 0.995   297.04 467.56 -170.51 0.635          
2 Σ Σ   526 796 -270.1 0.661   18.985 18.869 0.116 1.006   44.93 28.19 16.74 1.594          
3 Π Π   422 431 -9.6 0.978   14.392 14.468 -0.076 0.995   1.66 0.00 1.65 338.551          
4 Π Π   422 431 -9.6 0.978   14.392 14.468 -0.076 0.995   1.66 0.00 1.65 338.551          
scaled by     0.8985 0.943
19 08 20 15 07

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.