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

Compare vibrational frequencies for two calculations for ZnCH2 (Zinc methylene)

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 A1 A1   2994 3054 -59.7 0.980   1.040 1.037 0.002 1.002   4.01 18.39 -14.39 0.218
2 A1 A1   1334 1356 -21.7 0.984   1.106 1.115 -0.009 0.992   30.53 12.44 18.09 2.455
3 A1 A1   639 676 -37.5 0.945   6.734 5.027 1.707 1.340   1.25 1.43 -0.18 0.872
4 B1 B1   2869 24470 -21601.4 0.117   1.258 1.253 0.005 1.004   5.81 0.00 5.81  
5 B2 B2   3130 3215 -85.2 0.974   1.124 1.129 -0.005 0.996   0.00 14.17 -14.17 0.000
6 B2 B2   640 663 -23.3 0.965   1.155 1.148 0.006 1.005   121.66 84.92 36.74 1.433
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.