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Compare vibrational frequencies for two calculations for CH3CSCH3 (Thioacetone)


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

scale factors=0.8985, 0.943 -0.455
  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 A1 A1   2997 3043 -46.1 0.985   1.100 1.103 -0.002 0.998   4.06 2.37 1.713
2 A1 A1   2877 2918 -40.7 0.986   1.041 1.038 0.004 1.003   29.78 13.24 2.249
3 A1 A1   1471 1467 4.2 1.003   1.113 1.098 0.015 1.014   0.49 1.40 0.352
4 A1 A1   1399 1375 24.0 1.017   1.213 1.223 -0.010 0.992   3.50 5.71 0.612
5 A1 A1   1277 1285 -8.0 0.994   3.271 3.727 0.878   172.56 74.01 2.332
6 A1 A1   1002 997 4.4 1.004   1.705 1.652 0.052 1.032   15.81 0.09 171.317
7 A1 A1   676 689 -12.4 0.982   4.507 4.460 0.047 1.011   5.52 0.24 22.999
8 A1 A1   360 363 -2.3 0.994   2.492 2.434 0.058 1.024   1.08 0.23 4.653
9 A2 A2   2914 2982 -68.0 0.977   1.100 1.101 -0.000 1.000   0.00 0.00  
10 A2 A2   1448 1441 7.4 1.005   1.051 1.053 -0.002 0.998   0.00 0.00  
11 A2 A2   912 904 8.0 1.009   1.210 1.206 0.003 1.003   0.00 0.00  
12 A2 A2   71 99 -27.5 0.722   1.019 1.021 -0.002 0.998   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.