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


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

scale factors=0.8985, 0.943 -0.151
  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 -4.5 0.999   1.092 1.090 0.001 1.001   0.00 0.00  
2 A Ag   3311 3293 18.5 1.006   1.027 1.027 -0.000 1.000   0.00 0.00  
3 A Ag   1667 1662 5.2 1.003   1.061 1.059 0.003 1.002   0.00 0.00  
4 A Ag   1121 1136 -15.7 0.986   1.165 1.157 0.008 1.007   0.00 0.00  
5 A Ag   399 466 -67.2 0.856   1.094 1.101 -0.007 0.993   0.00 0.00  
6 A Ag   114 145 -30.9 0.787   4.593 4.744 0.968   0.00 0.00  
7 A Au   3431 3447 -15.8 0.995   1.090 1.089 0.001 1.001   0.80 1.55 0.517
8 A Au   1678 1677 1.3 1.001   1.068 1.068 0.000 1.000   42.21 38.45 1.098
9 A Au   212 248 -35.9 0.855   1.035 1.036 -0.000 1.000   139.57 132.33 1.055
10 A Au   80 99 -18.8 0.810   1.014 1.015 -0.001 0.999   28.36 31.93 0.888
11 A Bg   3431 3446 -15.9 0.995   1.091 1.089 0.001 1.001   0.00 0.00  
12 A Bg   1667 1663 3.8 1.002   1.064 1.062 0.002 1.002   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.