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

Compare vibrational frequencies for two calculations for NH3NH3 (Ammonia Dimer)

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 Ag   3434 3438 -4.7 0.999   1.092 1.090 0.001 1.001   0.00 0.00 0.00  
2 A Ag   3311 3293 18.3 1.006   1.027 1.027 -0.000 1.000   0.00 0.00 0.00  
3 A Ag   1667 1662 4.9 1.003   1.061 1.059 0.003 1.002   0.00 0.00 0.00  
4 A Ag   1121 1137 -16.2 0.986   1.165 1.156 0.009 1.007   0.00 0.00 0.00  
5 A Ag   399 466 -67.7 0.855   1.094 1.100 -0.007 0.994   0.00 0.00 0.00  
6 A Ag   114 144 -29.7 0.794   4.593 4.754 -0.160 0.966   0.00 0.00 0.00  
7 A Au   3431 3447 -15.8 0.995   1.090 1.089 0.001 1.001   0.80 1.58 -0.78 0.505
8 A Au   1678 1677 1.4 1.001   1.068 1.068 0.000 1.000   42.21 38.43 3.79 1.099
9 A Au   212 247 -34.9 0.859   1.035 1.036 -0.000 1.000   139.57 132.73 6.84 1.052
10 A Au   80 101 -20.7 0.795   1.014 1.015 -0.001 0.999   28.36 31.68 -3.32 0.895
11 A Bg   3431 3446 -15.9 0.995   1.091 1.089 0.001 1.001   0.00 0.00 0.00  
12 A Bg   1667 1663 4.1 1.002   1.064 1.062 0.002 1.002   0.00 0.00 0.00  
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.