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

Compare vibrational frequencies in CCCBDB for C4H2 (Diacetylene)

HF/aug-cc-pVDZ

Frequency in cm-1
  Calculated   Experimental
Mode Number Symmetry Frequency diff Symmetry Frequency Comment
1 Σg 3305 12 Σg+ 3293  
2 Σg 2261 77 Σg+ 2184  
3 Σg 854 -20 Σg+ 874  
4 Σu 3304 -25 Σu+ 3329  
5 Σu 2077 57 Σu+ 2020  
6 Πg 687 60 Πg 627  
7 Πg 393 -89 Πg 482  
8 Πu 702 72 Πu 630  
9 Πu 218 -13 Πu 231  
The calculated vibrational frequencies were scaled by 0.9106

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.