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Compare vibrational frequencies in CCCBDB for C4H2 (Diacetylene)

MP3/6-31G*

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 3532 3315   22 Σg+   3293  
2 Σg 2363 2218   34 Σg+   2184  
3 Σg 917 860   -14 Σg+   874  
4 Σu 3533 3316   -13 Σu+   3329  
5 Σu 2175 2041   21 Σu+   2020  
6 Πg 615 577   -50 Πg   627  
7 Πg 313 294   -188 Πg   482  
8 Πu 519 487   -143 Πu   630  
9 Πu 243 229   -2 Πu   231  
The calculated vibrational frequencies were scaled by 0.9386

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.