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

Compare vibrational frequencies in CCCBDB for C4H6O2 (2,3-Butanedione)

mPW1PW91/3-21G*

Frequency in cm-1
  Calculated   Experimental
Mode Number Symmetry Frequency diff Symmetry Frequency Comment
1 Ag 3043 25 Ag 3018  
2 Ag 2935 5 Ag 2930  
3 Ag 1691 -28 Ag 1719  
4 Ag 1435 11 Ag 1424  
5 Ag 1374 8 Ag 1366  
6 Ag 1212 -62 Ag 1274  
7 Ag 983 -21 Ag 1004  
8 Ag 649 -36 Ag 685  
9 Ag 523 -91 Ag 614  
10 Ag 360 -9 Ag 369  
11 Au 2993 3 Au 2990  
12 Au 1451 30 Au 1421  
13 Au 962 -149 Au 1111  
14 Au 374 35 Au 339  
15 Au 116        
16 Au 36 -12 Au 48  
17 Bg 2993 15 Bg 2978  
18 Bg 1457 33 Bg 1424  
19 Bg 1063 -46 Bg 1109  
20 Bg 651 113 Bg 538  
21 Bg 61 -179 Bg 240  
22 Bu 3043 32 Bu 3011  
23 Bu 2935 9 Bu 2926  
24 Bu 1685 -33 Bu 1718  
25 Bu 1437 16 Bu 1421  
26 Bu 1373 20 Bu 1353  
27 Bu 1105 -6 Bu 1111  
28 Bu 884 -43 Bu 927  
29 Bu 511 -23 Bu 534  
30 Bu 240 -10 Bu 250  
The calculated vibrational frequencies were scaled by 0.9496

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.