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Compare vibrational frequencies for two calculations for CH3OH+ (Methyl alcohol cation)


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)   Raman Activity (Å4/u)
mode number A B   A B diff. ratio   A B diff. ratio   A B diff. ratio   A B diff. ratio
1 A' A'   3368 3286 81.7 1.025   1.068 1.069 -0.001 0.999   342.91 283.87 59.03 1.208   36.07 38.34 -2.27 0.941
2 A' A'   3090 3121 -31.0 0.990   1.113 1.104 0.009 1.008   14.71 21.34 -6.63 0.689     44.63    
3 A' A'   2906 2794 111.7 1.040   1.025 1.032 -0.007 0.993   12.43 161.01 -148.58 0.077   102.33 233.98 -131.66 0.437
4 A' A'   1431 1436 -5.2 0.996   1.081 1.091 -0.009 0.992   6.12 7.76 -1.65 0.788     9.86    
5 A' A'   1382 1284 97.7 1.076   1.069 1.103 -0.034 0.970   31.55 141.24 -109.69 0.223   13.45 57.46 -44.01 0.234
6 A' A'   1206 1232 -26.5 0.978   1.304 1.361 -0.057 0.958   21.01 9.90 11.11 2.122     6.93    
7 A' A'   937 995 -57.9 0.942   1.119 1.104 0.014 1.013   143.28 70.36 72.92 2.036   0.82 6.03 -5.21 0.137
8 A' A'   670 717 -47.2 0.934   5.957 4.897 1.061 1.217   15.13 114.64 -99.51 0.132     69.80    
9 A" A"   3000 2851 149.3 1.052   1.107 1.086 0.020 1.019   14.25 59.95 -45.70 0.238   41.86 90.34 -48.48 0.463
10 A" A"   1423 1370 53.1 1.039   1.054 1.054 0.000 1.000   33.10 54.29 -21.19 0.610     9.23    
11 A" A"   979 890 88.9 1.100   1.166 1.125 0.042 1.037   0.26 24.01 -23.74 0.011   3.05 1.76 1.30 1.737
12 A" A"   42i 336i 294.0 0.125   1.123 1.208 -0.085 0.930   138.79 45.55 93.24 3.047     9.07    
scaled by     0.8985 0.943
19 08 20 15 07

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.