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

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

MP4/3-21G

Frequency in cm-1
  Calculated   Experimental
Mode Number Symmetry Frequency diff Symmetry Frequency Comment
1 Ag 3047 29 Ag 3018  
2 Ag 2955 25 Ag 2930  
3 Ag 1579 -140 Ag 1719  
4 Ag 1481 57 Ag 1424  
5 Ag 1408 42 Ag 1366  
6 Ag 1198 -76 Ag 1274  
7 Ag 980 -24 Ag 1004  
8 Ag 616 -69 Ag 685  
9 Ag 510 -104 Ag 614  
10 Ag 353 -16 Ag 369  
11 Au 3016 26 Au 2990  
12 Au 1503 82 Au 1421  
13 Au 993 -118 Au 1111  
14 Au 363 24 Au 339  
15 Au 117        
16 Au 54 6 Au 48  
17 Bg 3016 38 Bg 2978  
18 Bg 1506 82 Bg 1424  
19 Bg 1076 -33 Bg 1109  
20 Bg 638 100 Bg 538  
21 Bg 82 -158 Bg 240  
22 Bu 3047 36 Bu 3011  
23 Bu 2955 29 Bu 2926  
24 Bu 1557 -161 Bu 1718  
25 Bu 1484 63 Bu 1421  
26 Bu 1407 54 Bu 1353  
27 Bu 1110 -1 Bu 1111  
28 Bu 860 -67 Bu 927  
29 Bu 504 -30 Bu 534  
30 Bu 231 -19 Bu 250  
The calculated vibrational frequencies were scaled by 0.9698

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.