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Compare vibrational frequencies for two calculations for HCCO (ketenyl radical)


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

scale factors=0.8985, 0.943 -2.626 3.372 2.711 -8.303 -0.968
  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'   3279 3176 103.0 1.032   1.123 1.099 0.023 1.021   106.78 41.80 2.555
2 A' A'   1880 2328 -448.2 0.807   9.103 11.728 0.776   89.18 1048.83 0.085
3 A' A'   1255 1235 19.5 1.016   8.097 4.725 1.714   15.88 27.38 0.580
4 A' A'   556 651 -94.4 0.855   4.006 1.295 3.094   2.10 158.78 0.013
5 A' A'   85 583 -497.5 0.146   1.447 9.750 0.148   168.96 29.46 5.734
6 A" A"   481 505 -23.2 0.954   3.649 4.617 0.790   9.33 4.88 1.914
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.