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Compare vibrational frequencies for two calculations for C4+ (Carbon tetramer 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   2136 1973 162.7 1.082   12.000 12.000 0.000 1.000   0.00 0.00  
2 Σg Σg   853 873 -20.3 0.977   12.000 12.000 0.000 1.000   0.00 0.00  
3 Σu Σu   1202 1423 -221.8 0.844   12.000 12.000 0.000 1.000   114.49 2262.61 0.051
4 Πg Πg   327 265 62.4 1.236   12.000 12.000 0.000 1.000   0.00 0.00  
5 Πg Πg   244 207 37.1 1.179   12.000 12.000 0.000 1.000   0.00 0.00  
6 Πu Πu   170 134 36.5 1.273   12.000 12.000 0.000 1.000   7.70 1.57 4.909
7 Πu Πu   146 129 17.0 1.132   12.000 12.000 0.000 1.000   6.33 7.38 0.858
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.