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Compare vibrational frequencies for two calculations for C3H6S (Thietane)


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

scale factors=0.8985, 0.943 0.297 0.367 -0.429
  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'   2986 3030 -44.3 0.985   1.111 1.110 0.001 1.001   45.52 24.62 1.849
2 A' A'   2948 3005 -56.4 0.981   1.106 1.108 -0.002 0.998   17.11 7.18 2.384
3 A' A'   2934 2961 -26.9 0.991   1.065 1.061 0.004 1.004   16.50 13.78 1.198
4 A' A'   2908 2946 -38.4 0.987   1.060 1.060 0.000 1.000   39.04 29.96 1.303
5 A' A'   1496 1484 12.6 1.009   1.126 1.120 0.006 1.005   1.84 1.64 1.120
6 A' A'   1463 1456 6.3 1.004   1.082 1.083 -0.001 0.999   1.77 3.69 0.480
7 A' A'   1262 1241 21.1 1.017   1.364 1.378 -0.014 0.990   4.64 2.69 1.727
8 A' A'   1189 1175 13.7 1.012   1.382 1.448 -0.065 0.955   0.67 1.50 0.443
9 A' A'   978 981 -2.8 0.997   1.325 1.360 -0.035 0.974   2.17 3.72 0.584
10 A' A'   907 931 -23.7 0.975   2.798 2.501 1.119   0.03 0.11 0.269
11 A' A'   826 853 -26.7 0.969   2.185 1.819 1.202   5.65 2.86 1.975
12 A' A'   700 692 7.6 1.011   1.626 2.054 0.791   4.41 2.51 1.752
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.