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Compare vibrational frequencies in CCCBDB for C4H2 (Diacetylene)

CISD/6-31G

18 11 26 13 55
Frequency in cm-1
  Calculated   Experimental
Mode Number Symmetry Frequency Scaled
Frequency
Harm.
diff
Fund.
diff
Symmetry Harmonic
Frequency
Fundamental
Frequency
Comment
1 Σg 3525 3306   13 Σg+   3293  
2 Σg 2355 2208   24 Σg+   2184  
3 Σg 906 849   -25 Σg+   874  
4 Σu 3524 3305   -24 Σu+   3329  
5 Σu 2133 2000   -20 Σu+   2020  
6 Πg 633 593   -34 Πg   627  
7 Πg 691i 648i   -1130 Πg   482  
8 Πu 622 583   -47 Πu   630  
9 Πu 174 163   -68 Πu   231  
The calculated vibrational frequencies were scaled by 0.9378

See section Calculated; Vibrations; Scale Factors; Set scaling factors to change the scale factors used here.
See section Calculated; Vibrations; Scale Factors; Calculate a scale factor to determine the least squares best scaling factor.
See section Calculated; Vibrations; Scale Factors; Scale factor uncertainty for information on where the above scaling factor is from.