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


A = HF/6-31G*
B = MP2/6-31G*

scale factors=0.8985, 0.943 0.261
  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 3292 24.3 1.007   1.029 1.028 0.001 1.001   14.00 9.94 1.409
2 A1 A1   2300 2386 -86.1 0.964   1.020 1.022 -0.002 0.998   88.38 67.97 1.300
3 A1 A1   1334 1320 14.1 1.011   1.187 1.186 0.001 1.001   181.12 150.40 1.204
4 A1 A1   1150 1162 -12.8 0.989   1.140 1.154 -0.013 0.988   173.52 108.20 1.604
5 A1 A1   543 638 -94.4 0.852   4.966 4.705 1.055   34.64 14.03 2.470
6 A2 A2   228 255 -26.8 0.895   1.008 1.008 0.000 1.000   0.00 0.00  
7 E E   3428 3422 6.4 1.002   1.094 1.092 0.001 1.001   42.13 40.63 1.037
8 E E   3428 3422 6.4 1.002   1.094 1.092 0.001 1.001   42.13 40.63 1.037
9 E E   2340 2457 -117.0 0.952   1.118 1.119 -0.000 1.000   322.40 226.34 1.424
10 E E   2340 2457 -117.0 0.952   1.118 1.119 -0.000 1.000   322.40 226.34 1.424
11 E E   1651 1636 15.5 1.009   1.056 1.055 0.001 1.001   35.56 34.06 1.044
12 E E   1651 1636 15.5 1.009   1.056 1.055 0.001 1.001   35.56 34.06 1.044
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.