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Compare vibrational frequencies in CCCBDB for C2H2 (Acetylene)

QCISD(TQ)/6-31G(2df,p)

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 3561 3561   187 Σg   3374  
2 Σg 2021 2021   47 Σg   1974  
3 Σu 3466 3466   177 Σu   3289  
4 Πg 491 491   -121 Πg   612  
5 Πu 767 767   37 Πu   730  
The calculated vibrational frequencies were scaled by 1

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.