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

Compare vibrational frequencies for two calculations for BH3NH3 (borane ammonia)

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 A1 A1   3316 3290 25.9 1.008   1.029 1.028 0.001 1.001   14.00 9.95 4.05 1.407
2 A1 A1   2300 2390 -89.4 0.963   1.020 1.022 -0.002 0.998   88.38 67.72 20.66 1.305
3 A1 A1   1334 1319 14.7 1.011   1.187 1.186 0.001 1.001   181.12 150.38 30.74 1.204
4 A1 A1   1150 1161 -11.7 0.990   1.140 1.153 -0.013 0.989   173.52 108.65 64.87 1.597
5 A1 A1   543 635 -91.5 0.856   4.966 4.722 0.244 1.052   34.64 14.32 20.32 2.418
6 A2 A2   228 255 -26.6 0.896   1.008 1.008 0.000 1.000   0.00 0.00 0.00  
7 E E   3428 3420 7.8 1.002   1.094 1.092 0.001 1.001   42.13 40.59 1.54 1.038
8 E E   3428 3420 7.8 1.002   1.094 1.092 0.001 1.001   42.13 40.59 1.54 1.038
9 E E   2340 2461 -120.9 0.951   1.118 1.119 -0.000 1.000   322.40 226.03 96.37 1.426
10 E E   2340 2461 -120.9 0.951   1.118 1.119 -0.000 1.000   322.40 226.03 96.37 1.426
11 E E   1651 1636 15.3 1.009   1.056 1.055 0.001 1.001   35.56 34.05 1.52 1.045
12 E E   1651 1636 15.3 1.009   1.056 1.055 0.001 1.001   35.56 34.05 1.52 1.045
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.