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Compare vibrational frequencies for two calculations for CH3CHCHCH2 (methylallyl radical)


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

scale factors=0.8985, 0.943 -0.207 -0.105 0.480
  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'   3073 3145 -72.1 0.977   1.118 1.118 0.000 1.000   22.24 9.48 2.347
2 A' A'   2992 3048 -55.7 0.982   1.067 1.058 0.010 1.009   22.24 10.13 2.194
3 A' A'   2990 3039 -48.6 0.984   1.085 1.086 -0.001 0.999   38.04 22.85 1.665
4 A' A'   2981 3023 -42.0 0.986   1.078 1.089 -0.011 0.990   6.86 7.99 0.858
5 A' A'   2934 3009 -74.9 0.975   1.100 1.101 -0.001 0.999   27.00 10.57 2.555
6 A' A'   2861 2909 -47.3 0.984   1.038 1.037 0.001 1.001   43.04 26.80 1.606
7 A' A'   1482 1488 -6.5 0.996   1.302 1.357 -0.055 0.960   2.94 7.49 0.393
8 A' A'   1476 1469 7.2 1.005   1.238 1.200 0.038 1.032   3.08 1.24 2.473
9 A' A'   1447 1441 6.4 1.004   1.458 1.665 0.876   5.07 13.60 0.373
10 A' A'   1407 1390 17.0 1.012   1.238 1.259 -0.021 0.983   1.57 2.02 0.779
11 A' A'   1307 1314 -6.8 0.995   1.323 1.428 0.927   1.01 0.03 35.939
12 A' A'   1215 1269 -54.4 0.957   2.322 1.842 1.261   1.20 1.91 0.628
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.