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Compare vibrational frequencies in CCCBDB for C4N2 (2-Butynedinitrile)

mPW1PW91/3-21G*

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 2452 2329   39 Σg   2290  
2 Σg 2238 2126   7 Σg   2119  
3 Σg 629 597   -95 Σg   692  
4 Σu 2374 2254   13 Σu   2241  
5 Σu 1208 1147   -7 Σu   1154  
6 Πg 952 904   400 Πg   504  
7 Πg 353 335   72 Πg   263  
8 Πu 718 681   209 Πu   472  
9 Πu 121 115   8 Πu   107  
The calculated vibrational frequencies were scaled by 0.9496

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.