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Compare vibrational frequencies in CCCBDB for C4H2 (Diacetylene)

CCSD(T)/aug-cc-pVDZ

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 3439 3310   17 Σg+   3293  
2 Σg 2207 2124   -60 Σg+   2184  
3 Σg 882 849   -25 Σg+   874  
4 Σu 3439 3310   -19 Σu+   3329  
5 Σu 2020 1944   -76 Σu+   2020  
6 Πg 540 520   -107 Πg   627  
7 Πg 662i 637i   -1119 Πg   482  
8 Πu 500 481   -149 Πu   630  
9 Πu 114 110   -121 Πu   231  
The calculated vibrational frequencies were scaled by 0.9625

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.