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Compare vibrational frequencies for two calculations for C4H6OS (4,5-dihydrothiophene-2-ol)


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

scale factors=0.8985, 0.943 -0.150
  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 A A   3676 3522 153.6 1.044   1.066 1.066 0.001 1.001   81.65 54.02 1.512
2 A A   3025 3063 -38.8 0.987   1.094 1.094 0.000 1.000   14.24 6.49 2.193
3 A A   2980 3024 -43.5 0.986   1.108 1.108 -0.000 1.000   17.95 8.48 2.117
4 A A   2931 2970 -38.8 0.987   1.065 1.093 -0.029 0.974   53.63 26.57 2.018
5 A A   2910 2955 -44.8 0.985   1.093 1.065 0.028 1.026   20.39 10.18 2.004
6 A A   2867 2899 -32.5 0.989   1.069 1.067 0.003 1.003   60.18 38.53 1.562
7 A A   1676 1613 63.9 1.040   7.600 7.750 0.981   186.39 115.82 1.609
8 A A   1486 1466 19.3 1.013   1.106 1.104 0.002 1.001   1.61 0.49 3.321
9 A A   1464 1447 16.8 1.012   1.089 1.092 -0.003 0.997   1.20 3.13 0.381
10 A A   1364 1339 24.7 1.018   1.793 1.790 0.003 1.002   12.89 12.37 1.042
11 A A   1325 1299 25.4 1.020   1.404 1.369 0.035 1.025   27.36 17.30 1.581
12 A A   1290 1267 23.0 1.018   1.319 1.349 -0.029 0.978   10.73 8.63 1.244
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.