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Compare vibrational frequencies for two calculations for CO2+ (Carbon dioxide 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   1218 1310 -91.6 0.930   15.995 15.995 0.000 1.000   0.00 0.00  
2 Σu Σu   865 1579i 2443.3 -0.548   12.877 12.877 0.000 1.000   229.49 1784.33 0.129
3 Πu Πu   550 549 0.8 1.001   12.877 12.877 0.000 1.000   59.12 61.56 0.960
4 Πu Πu   383 547 -163.5 0.701   12.877 12.877 0.000 1.000   41.87 32.69 1.281
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.