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Compare vibrational frequencies for two calculations for H2O2+ (Hydrogen peroxide cation)


A = HF/6-31G*
B = MP2/6-31G*

scale factors=0.8985, 0.943 -0.430
  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 Ag Ag   3357 3214 143.5 1.045   1.075 1.073 0.002 1.002   0.00 0.00  
2 Ag Ag   1567 1493 73.5 1.049   1.178 1.155 0.023 1.020   0.00 0.00  
3 Ag Ag   1404 1009 395.6 1.392   14.398 14.828 0.971   0.00 0.00  
4 Au Au   873 824 49.5 1.060   1.067 1.067 0.000 1.000   388.11 372.17 1.043
5 Bu Bu   3315 5480 -2164.6 0.605   1.067 1.067 0.000 1.000   1219.06 886362.90 0.001
6 Bu Bu   1290 1268 22.6 1.018   1.067 1.067 0.000 1.000   321.07 577.19 0.556
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.