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Compare vibrational frequencies for two calculations for C5H5NO (2(3H)-Pyridinone)


A = HF/6-31G*
B = MP2/6-31G*

scale factors=0.8985, 0.943 0.617 0.652 -0.172 -0.101
  symmetry   frequency (cm-1)   reduced mass (amu)   IR Intensity (km mol-1)
mode number A B   A B diff. ratio   A B diff. ratio   A B diff. ratio
1 A A   3052 3074 -21.5 0.993   1.100 1.099 0.001 1.001   15.92 9.69 1.642
2 A A   3027 3050 -23.2 0.992   1.089 1.089 0.001 1.001   9.01 2.70 3.338
3 A A   2993 3000 -7.2 0.998   1.092 1.090 0.001 1.001   38.73 30.82 1.257
4 A A   2931 2992 -61.2 0.980   1.093 1.093 0.000 1.000   4.27 1.22 3.503
5 A A   2876 2890 -13.9 0.995   1.070 1.069 0.001 1.001   4.91 0.67 7.277
6 A A   1818 1697 121.4 1.072   12.544 11.927 1.052   400.82 169.77 2.361
7 A A   1703 1612 90.6 1.056   6.227 5.575 1.117   96.71 22.96 4.212
8 A A   1627 1534 92.2 1.060   8.958 9.130 0.981   185.01 52.27 3.540
9 A A   1417 1407 10.0 1.007   1.128 1.092 0.036 1.033   5.39 18.36 0.294
10 A A   1406 1371 34.8 1.025   1.592 1.643 -0.050 0.969   64.30 26.33 2.442
11 A A   1381 1349 31.9 1.024   1.407 1.398 0.009 1.006   10.26 8.85 1.159
12 A A   1336 1277 58.2 1.046   1.736 1.837 0.945   4.09 7.85 0.522
scaled by     0.8985 0.943

See section III.C.1 List or set vibrational scaling factors to change the scale factors used here.
See section III.C.2 Calculate a vibrational scaling factor for a given set of molecules to determine the least squares best scaling factor.