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

Compare vibrational frequencies for two calculations for HCCCN+ (Cyanoacetylene cation)

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 Σ Σ   3154 4010 -855.9 0.787   1.132 7.746 -6.614 0.146   201.13 4107.33 -3906.20 0.049
2 Σ Σ   1807 3099 -1292.1 0.583   7.492 1.229 6.262 6.094   100.07 35.47 64.61 2.822
3 Σ Σ   1542 2339 -797.2 0.659   11.713 6.195 5.518 1.891   428.74 717.54 -288.81 0.598
4 Σ Σ   848 898 -49.6 0.945   8.842 8.956 -0.115 0.987   43.99 147.76 -103.77 0.298
5 Π Π   829 926 -97.2 0.895   1.367 1.279 0.088 1.069   12.83 27.87 -15.04 0.460
6 Π Π   631 720 -89.3 0.876   1.292 10.320 -9.029 0.125   64.38 13.61 50.77 4.732
7 Π Π   440 609 -169.3 0.722   7.781 11.808 -4.027 0.659   3.81 0.12 3.69 31.020
8 Π Π   432 436 -4.0 0.991   6.899 1.311 5.588 5.264   9.34 41.12 -31.78 0.227
9 Π Π   201 245 -44.0 0.821   5.327 5.422 -0.095 0.982   0.02 0.49 -0.47 0.033
10 Π Π   200 241 -40.5 0.832   6.179 4.637 1.542 1.333   0.22 0.42 -0.20 0.524
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.