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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 = 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   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   2340 2461 -120.9 0.951   1.118 1.119 -0.000 1.000   322.40 226.03 96.37 1.426
9 E E   1651 1636 15.3 1.009   1.056 1.055 0.001 1.001   35.56 34.05 1.52 1.045
10 E E   1162 1167 -4.6 0.996   1.076 1.066 0.009 1.009   16.17 5.81 10.37 2.785
11 E E   1018 1036 -18.7 0.982   1.301 1.327 -0.026 0.980   54.52 45.10 9.42 1.209
12 E E   612 623 -10.7 0.983   1.044 1.045 -0.001 0.999   2.05 3.01 -0.96 0.680
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.