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IV.C.1. (XIII.D.1.)

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

HF/CEP-31G*

Frequency in cm-1
  Calculated   Experimental
Mode Number Symmetry Frequency diff Symmetry Frequency Comment
1 Σg 2442 152 Σg 2290  
2 Σg 2225 106 Σg 2119  
3 Σg 568 -124 Σg 692  
4 Σu 2372 131 Σu 2241  
5 Σu 1090 -64 Σu 1154  
6 Πg 559 55 Πg 504  
7 Πg 295 32 Πg 263  
8 Πu 499 27 Πu 472  
9 Πu 117 10 Πu 107  
The calculated vibrational frequencies were scaled by 0.898

See section XIII.C.3 List or set vibrational scaling factors to change the scale factors used here.
See section III.B.3.c Calculate a vibrational scaling factor for a set of molecules to determine the least squares best scaling factor.
See section III.B.3.b List of vibrational scaling factors and their uncertainties for information on where the above scaling factor is from.