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Compare vibrational frequencies for two calculations for SiCl3CH3 (methyltrichlorosilane)


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 A1 A1   2883 2932 -48.4 0.984   1.035 1.035 0.000 1.000   0.43 0.78 -0.34 0.559          
2 A1 A1   1319 1299 20.1 1.015   1.237 1.246 -0.010 0.992   25.02 31.55 -6.53 0.793          
3 A1 A1   711 735 -24.7 0.966   5.439 5.232 0.207 1.040   84.81 80.20 4.61 1.057          
4 A1 A1   425 436 -11.3 0.974   12.991 13.075 -0.084 0.994   26.29 21.39 4.90 1.229          
5 A1 A1   225 226 -1.6 0.993   14.139 14.271 -0.132 0.991   19.53 15.49 4.05 1.261          
6 A2 A2   158 186 -28.7 0.846   1.016 1.016 -0.000 1.000   0.00 0.00 0.00            
7 E E   2958 3029 -71.0 0.977   1.102 1.102 0.000 1.000   3.12 0.25 2.87 12.346          
8 E E   2958 3029 -71.0 0.977   1.102 1.102 0.000 1.000   3.12 0.25 2.87 12.346          
9 E E   1431 1425 5.4 1.004   1.049 1.049 -0.000 1.000   4.33 4.87 -0.55 0.888          
10 E E   1431 1425 5.4 1.004   1.049 1.049 -0.000 1.000   4.33 4.87 -0.55 0.888          
11 E E   819 825 -6.2 0.992   1.361 1.381 -0.020 0.985   96.53 98.89 -2.36 0.976          
12 E E   819 825 -6.2 0.992   1.361 1.381 -0.020 0.985   96.53 98.89 -2.36 0.976          
13 E E   554 573 -19.6 0.966   12.169 10.940 1.229 1.112   191.95 161.81 30.14 1.186          
14 E E   554 573 -19.6 0.966   12.170 10.940 1.229 1.112   191.95 161.81 30.14 1.186          
15 E E   211 212 -1.0 0.995   4.884 4.902 -0.018 0.996   6.53 4.73 1.81 1.382          
16 E E   211 212 -1.0 0.995   4.884 4.902 -0.018 0.996   6.53 4.73 1.81 1.382          
17 E E   150 150 0.8 1.006   7.375 7.222 0.153 1.021   0.74 0.65 0.09 1.131          
18 E E   150 150 0.8 1.006   7.375 7.222 0.153 1.021   0.74 0.65 0.09 1.131          
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.