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

Compare vibrational frequencies for two calculations for C6H12 (trans-1,3-dimethylcyclobutane)

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 Ag Ag   2921 2997 -75.9 0.975   1.101 1.103 -0.002 0.999   0.00 0.00 0.00  
2 Ag Ag   2900 2942 -41.6 0.986   1.076 1.086 -0.010 0.991   0.00 0.00 0.00  
3 Ag Ag   2883 2928 -44.9 0.985   1.074 1.062 0.012 1.011   0.00 0.00 0.00  
4 Ag Ag   2864 2913 -48.5 0.983   1.036 1.035 0.001 1.001   0.00 0.00 0.00  
5 Ag Ag   1481 1471 10.1 1.007   1.129 1.048 0.081 1.077   0.00 0.00 0.00  
6 Ag Ag   1474 1465 9.2 1.006   1.048 1.118 -0.071 0.937   0.00 0.00 0.00  
7 Ag Ag   1404 1380 24.3 1.018   1.322 1.304 0.018 1.014   0.00 0.00 0.00  
8 Ag Ag   1354 1334 19.4 1.015   1.381 1.460 -0.079 0.946   0.00 0.00 0.00  
9 Ag Ag   1228 1216 12.7 1.010   1.411 1.441 -0.031 0.979   0.00 0.00 0.00  
10 Ag Ag   1072 1094 -22.0 0.980   2.392 2.244 0.148 1.066   0.00 0.00 0.00  
11 Ag Ag   935 928 7.5 1.008   1.122 1.121 0.001 1.001   0.00 0.00 0.00  
12 Ag Ag   853 857 -3.9 0.995   3.739 3.489 0.250 1.072   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.