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Compare vibrational frequencies in CCCBDB for C4H2 (Diacetylene)

MP2=FULL/3-21G*

17 05 22 16 49
Frequency in cm-1
  Calculated   Experimental
Mode Number Symmetry Frequency diff Symmetry Frequency Comment
1 Σg 3292 -1 Σg+ 3293  
2 Σg 2097 -87 Σg+ 2184  
3 Σg 823 -51 Σg+ 874  
4 Σu 3291 -38 Σu+ 3329  
5 Σu 1901 -119 Σu+ 2020  
6 Πg 548 -79 Πg 627  
7 Πg 693i -1175 Πg 482  
8 Πu 497 -133 Πu 630  
9 Πu 120 -111 Πu 231  
The calculated vibrational frequencies were scaled by 0.948

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.