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

Compare vibrational frequencies for two calculations for C2H7+ (Ethane, protonated)

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 A A   3115 3153 -37.6 0.988   1.119 1.119 -0.000 1.000   12.25 12.64 -0.39 0.969
2 A A   3078 3095 -17.3 0.994   1.111 1.096 0.015 1.014   31.15 45.74 -14.59 0.681
3 A A   2945 2954 -8.9 0.997   1.024 1.037 -0.013 0.988   1.45 2.46 -1.02 0.588
4 A A   1682 1992 -310.2 0.844   1.102 1.097 0.004 1.004   8.93 45.93 -36.99 0.195
5 A A   1413 1424 -10.8 0.992   1.056 1.045 0.011 1.011   0.14 2.00 -1.86 0.069
6 A A   1394 1404 -10.2 0.993   1.099 1.074 0.024 1.023   30.74 36.03 -5.29 0.853
7 A A   1344 1338 5.8 1.004   1.067 1.044 0.022 1.021   0.00 0.64 -0.64 0.007
8 A A   1062 1088 -25.9 0.976   1.200 1.264 -0.064 0.949   0.01 0.25 -0.23 0.060
9 A A   761 842 -81.0 0.904   1.081 1.035 0.047 1.045   1.89 4.01 -2.12 0.470
10 A A   257 336 -78.7 0.766   3.392 4.501 -1.109 0.754   4.02 4.87 -0.85 0.826
11 A A   179 240 -61.2 0.745   1.032 1.042 -0.009 0.991   0.36 1.71 -1.36 0.208
12 A A   3116 3156 -40.7 0.987   1.117 1.116 0.001 1.001   30.82 48.44 -17.62 0.636
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.