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III.G.7. (XIII.B.3.) (XIII.D.5.)

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
  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 3144 -64.8 0.979   1.095 1.111 -0.017 0.985   5.48 1.12 4.36 4.876
2 A' A'   2954 3036 -81.5 0.973   1.101 1.104 -0.003 0.998   39.39 12.74 26.66 3.093
3 A' A'   2928 2961 -32.4 0.989   1.084 1.084 -0.000 1.000   12.58 10.92 1.66 1.152
4 A' A'   2873 2932 -58.5 0.980   1.038 1.036 0.002 1.002   36.43 20.38 16.06 1.788
5 A' A'   1491 1811 -320.4 0.823   1.476 6.844 -5.368 0.216   2.76 3.55 -0.79 0.777
6 A' A'   1441 1467 -25.7 0.982   1.784 1.049 0.735 1.701   2.82 7.86 -5.04 0.358
7 A' A'   1403 1384 18.6 1.013   1.237 1.259 -0.022 0.983   1.50 2.31 -0.81 0.650
8 A' A'   1218 1258 -40.6 0.968   1.470 1.222 0.248 1.203   1.79 1.95 -0.17 0.915
9 A' A'   1102 1104 -1.8 0.998   1.905 2.043 -0.137 0.933   6.63 7.95 -1.32 0.834
10 A' A'   898 922 -24.2 0.974   1.568 1.706 -0.138 0.919   0.07 2.72 -2.65 0.025
11 A' A'   822 817 5.1 1.006   1.493 1.302 0.191 1.147   11.05 16.45 -5.40 0.672
12 A' A'   399 402 -2.5 0.994   2.362 2.292 0.070 1.030   4.92 7.96 -3.04 0.618
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.