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Compare vibrational frequencies for two calculations for C4H6S (Thiophene, 2,3-dihydro-)


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

scale factors=0.8985, 0.943 0.317
  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   3073 3098 -24.9 0.992   1.102 1.101 0.001 1.001   12.04 6.46 1.864
2 A A   3036 3070 -33.3 0.989   1.089 1.088 0.001 1.001   5.56 1.00 5.559
3 A A   2980 3025 -45.3 0.985   1.107 1.107 0.000 1.000   17.57 7.74 2.270
4 A A   2930 2975 -45.2 0.985   1.068 1.096 -0.028 0.975   55.67 20.67 2.693
5 A A   2912 2953 -41.0 0.986   1.091 1.063 0.027 1.026   13.58 13.56 1.001
6 A A   2870 2903 -32.9 0.989   1.069 1.067 0.002 1.002   46.67 27.84 1.677
7 A A   1639 1556 83.3 1.054   6.392 6.075 1.052   7.45 7.55 0.986
8 A A   1480 1460 19.1 1.013   1.106 1.105 0.001 1.001   0.94 0.78 1.201
9 A A   1460 1444 15.7 1.011   1.088 1.093 -0.006 0.995   1.09 2.49 0.436
10 A A   1338 1304 33.8 1.026   1.645 1.682 -0.038 0.978   0.23 0.68 0.346
11 A A   1314 1293 20.8 1.016   1.330 1.293 0.037 1.028   3.44 3.66 0.939
12 A A   1273 1250 23.7 1.019   1.250 1.280 -0.030 0.977   17.54 17.08 1.027
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.