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Compare vibrational frequencies for two calculations for H2OH2CO (water formaldehyde dimer)


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

scale factors=0.8985, 0.943 3.497
  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   3744 3659 84.5 1.023   1.081 1.078 0.003 1.003   118.29 89.54 1.321
2 A A   3634 3513 121.2 1.034   1.048 1.049 -0.001 0.999   85.36 97.82 0.873
3 A A   2947 2970 -23.0 0.992   1.119 1.121 -0.002 0.998   73.03 58.51 1.248
4 A A   2864 2875 -11.4 0.996   1.053 1.049 0.004 1.004   54.16 54.27 0.998
5 A A   1803 1664 139.7 1.084   7.074 3.577 1.978   150.99 30.43 4.962
6 A A   1659 1659 0.0 1.000   1.079 1.163 -0.085 0.927   101.81 97.27 1.047
7 A A   1503 1483 20.7 1.014   1.106 1.205 -0.099 0.918   15.75 10.85 1.451
8 A A   1247 1226 21.3 1.017   1.338 1.325 0.013 1.010   16.97 4.73 3.584
9 A A   1212 1157 55.0 1.048   1.363 1.355 0.009 1.006   0.77 4.56 0.169
10 A A   471 556 -85.1 0.847   1.056 1.046 0.010 1.009   246.88 247.85 0.996
11 A A   274 313 -39.1 0.875   1.103 1.082 0.021 1.020   115.42 86.39 1.336
12 A A   171 215 -43.6 0.797   1.098 1.084 0.014 1.013   27.62 41.21 0.670
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.