return to home page

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

Compare vibrational frequencies for two calculations for OCS (Carbonyl sulfide)

A = HF/6-31G*

B = MP2FC/6-31G*

  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 Σ Σ   2122 2942 -820.0 0.721   13.409 13.233 0.176 1.013   209.49 2772.23 -2562.74 0.076
2 Σ Σ   799 847 -48.6 0.943   19.417 19.724 -0.307 0.984   46.78 7.11 39.67 6.580
3 Π Π   509 468 41.0 1.088   13.031 13.035 -0.003 1.000   19.77 3.97 15.80 4.979
4 Π Π   383 468 -85.2 0.818   13.028 13.035 -0.007 0.999   26.38 3.97 22.41 6.644
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.