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

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

HF/3-21G*

Frequency in cm-1
  Calculated   Experimental
Mode Number Symmetry Frequency diff Symmetry Frequency Comment
1 Σg 2442 152 Σg 2290  
2 Σg 2217 98 Σg 2119  
3 Σg 582 -110 Σg 692  
4 Σu 2359 118 Σu 2241  
5 Σu 1108 -46 Σu 1154  
6 Πg 889 385 Πg 504  
7 Πg 346 83 Πg 263  
8 Πu 643 171 Πu 472  
9 Πu 121 14 Πu 107  
The calculated vibrational frequencies were scaled by 0.9026

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.