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Compare vibrational frequencies for two calculations for CH3CHCH (1-propenyl radical)


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

scale factors=0.8985, 0.943 -5.361 0.735 0.249 -0.140 -0.139 0.191
  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'   3080 3145 -65.6 0.979   1.095 1.111 -0.017 0.985   5.48 1.11 4.933
2 A' A'   2954 3036 -82.0 0.973   1.101 1.104 -0.003 0.998   39.39 12.72 3.096
3 A' A'   2928 2961 -32.5 0.989   1.084 1.084 -0.000 1.000   12.58 10.94 1.150
4 A' A'   2873 2932 -58.5 0.980   1.038 1.036 0.002 1.002   36.43 20.36 1.789
5 A' A'   1491 1809 -318.6 0.824   1.476 6.837 0.216   2.76 3.55 0.777
6 A' A'   1441 1467 -25.6 0.983   1.784 1.049 1.701   2.82 7.86 0.359
7 A' A'   1403 1384 18.8 1.014   1.237 1.259 -0.022 0.983   1.50 2.30 0.654
8 A' A'   1218 1258 -40.5 0.968   1.470 1.221 1.204   1.79 1.96 0.914
9 A' A'   1102 1103 -1.4 0.999   1.905 2.045 0.932   6.63 7.95 0.833
10 A' A'   898 922 -24.0 0.974   1.568 1.706 0.919   0.07 2.71 0.025
11 A' A'   822 816 6.0 1.007   1.493 1.303 1.146   11.05 16.51 0.670
12 A' A'   399 402 -2.5 0.994   2.362 2.290 0.072 1.032   4.92 7.97 0.617
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.