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Compare vibrational frequencies for two calculations for C3H7NO (Propanamide)


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

scale factors=0.8985, 0.943 1.171
  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   3562 3537 24.8 1.007   1.105 1.103 0.002 1.002   50.36 39.91 1.262
2 A A   3447 3411 35.9 1.011   1.047 1.046 0.001 1.001   51.65 43.74 1.181
3 A A   2971 3043 -72.0 0.976   1.104 1.104 0.000 1.000   32.68 14.90 2.193
4 A A   2952 3029 -76.6 0.975   1.101 1.103 -0.002 0.998   35.88 17.87 2.007
5 A A   2904 2965 -61.6 0.979   1.100 1.102 -0.002 0.998   20.16 10.77 1.871
6 A A   2895 2946 -51.0 0.983   1.041 1.037 0.004 1.004   29.67 17.58 1.687
7 A A   2874 2919 -45.1 0.985   1.063 1.062 0.001 1.001   28.87 16.26 1.775
8 A A   1780 1713 66.9 1.039   9.533 8.361 1.140   382.03 223.48 1.709
9 A A   1614 1569 45.4 1.029   1.224 1.247 -0.023 0.981   126.75 104.12 1.217
10 A A   1477 1474 3.2 1.002   1.070 1.055 0.015 1.014   10.18 9.66 1.054
11 A A   1472 1469 3.1 1.002   1.040 1.041 -0.002 0.998   3.88 5.83 0.666
12 A A   1454 1448 6.0 1.004   1.087 1.086 0.000 1.000   3.53 5.58 0.632
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.