return to home page

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

Compare vibrational frequencies for two calculations for C4 (Carbon tetramer)

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 Σg Σg   2136 2020 115.6 1.057   12.000 12.000 0.000 1.000   0.00 0.00 0.00  
2 Σg Σg   918 895 23.2 1.026   12.000 12.000 0.000 1.000   0.00 0.00 0.00  
3 Σu Σu   1564 1493 70.9 1.047   12.000 12.000 0.000 1.000   142.35 491.73 -349.38 0.289
4 Πg Πg   367 370 -4.0 0.989   12.000 12.000 0.000 1.000   0.00 0.00 0.00  
5 Πu Πu   188 169 19.2 1.114   12.000 12.000 0.000 1.000   25.62 16.58 9.04 1.545
6 Πu Πu   170 169 1.4 1.008   12.000 12.000 0.000 1.000   7.70 16.58 -8.88 0.465
7 Πu Πu   146 169 -23.3 0.862   12.000 12.000 0.000 1.000   6.33 16.58 -10.25 0.382
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.