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Compare vibrational frequencies for two calculations for CS2+ (Carbon disulfide 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 Σg Σg   595 677 -81.8 0.879   31.972 31.972 0.000 1.000   0.00 0.00  
2 Σu Σu   1035 1014 21.2 1.021   13.314 13.314 0.000 1.000   381.93 11.40 33.494
3 Πu Πu   357 369 -11.7 0.968   13.314 13.314 0.000 1.000   0.82 5.49 0.150
4 Πu Πu   279 342 -62.7 0.816   13.314 13.314 0.000 1.000   0.66 2.07 0.317
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.