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Compare vibrational frequencies for two calculations for N2H4+ (hydrazine cation)


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

scale factors=0.8985, 0.943 0.133 -0.911
  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 Ag Ag   3380 3360 20.4 1.006   1.058 1.054 0.003 1.003   0.00 0.00  
2 Ag Ag   1687 1637 50.0 1.031   1.323 1.191 1.111   0.00 0.00  
3 Ag Ag   1408 1361 47.0 1.035   2.819 3.731 0.756   0.00 0.00  
4 Ag Ag   264 420 -156.1 0.628   1.414 1.408 0.006 1.004   0.00 0.00  
5 Au Au   3499 3487 11.9 1.003   1.109 1.109 0.000 1.000   468.75 428.83 1.093
6 Au Au   1012 1009 2.9 1.003   1.032 1.030 0.002 1.002   15.90 14.41 1.103
7 Au Au   604 578 25.6 1.044   1.010 1.012 -0.002 0.998   8.41 19.96 0.421
8 Bg Bg   3484 3472 12.2 1.004   1.121 1.118 0.002 1.002   0.00 0.00  
9 Bg Bg   1374 1353 22.0 1.016   1.400 1.387 0.013 1.010   0.00 0.00  
10 Bu Bu   3350 3349 0.9 1.000   1.041 1.041 0.000 1.000   438.97 196.94 2.229
11 Bu Bu   1587 1560 27.2 1.017   1.101 1.102 -0.000 1.000   164.71 117.72 1.399
12 Bu Bu   505 568 -63.3 0.889   1.141 1.140 0.000 1.000   635.59 567.18 1.121
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.