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

Compare vibrational frequencies in CCCBDB for C2H2O2 (Ethanedial)

MP2/3-21G*

Frequency in cm-1
  Calculated   Experimental
Mode Number Symmetry Frequency diff Symmetry Frequency Comment
1 Ag 2876 33 Ag 2843  
2 Ag 1521 -224 Ag 1745  
3 Ag 1327 -11 Ag 1338  
4 Ag 970 -95 Ag 1065  
5 Ag 515 -36 Ag 551  
6 Au 830 29 Au 801  
7 Au 194 67 Au 127  
8 Bg 1051 3 Bg 1048  
9 Bu 2875 40 Bu 2835  
10 Bu 1498 -234 Bu 1732  
11 Bu 1307 -5 Bu 1312  
12 Bu 296 -43 Bu 339  
The calculated vibrational frequencies were scaled by 0.9513

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.