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

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

HF/6-311+G(3df,2p)

Frequency in cm-1
  Calculated   Experimental
Mode Number Symmetry Frequency diff Symmetry Frequency Comment
1 Σg 2431 141 Σg 2290  
2 Σg 2230 111 Σg 2119  
3 Σg 575 -117 Σg 692  
4 Σu 2374 133 Σu 2241  
5 Σu 1098 -56 Σu 1154  
6 Πg 582 78 Πg 504  
7 Πg 288 25 Πg 263  
8 Πu 513 41 Πu 472  
9 Πu 113 6 Πu 107  
The calculated vibrational frequencies were scaled by 0.9086

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.