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III.G.7. (XIII.B.3.) (XIII.D.5.)

Compare vibrational frequencies for two calculations for H2OHCOOH (Water formic acid dimer 2)

A = HF/6-31G*

B = MP2/6-31G*

scale factors=0.8985, 0.943
  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 84.8 1.023   1.081 1.079 0.002 1.002   114.63 90.75 23.89 1.263
2 A A   3635 3518 117.1 1.033   1.048 1.048 -0.000 1.000   51.47 77.48 -26.01 0.664
3 A A   3629 3472 156.8 1.045   1.065 1.064 0.001 1.001   140.83 81.22 59.61 1.734
4 A A   3017 3026 -9.1 0.997   1.098 1.096 0.002 1.002   21.22 10.90 10.32 1.947
5 A A   1800 1708 91.7 1.054   7.876 7.824 0.052 1.007   484.77 298.40 186.37 1.625
6 A A   1657 1656 0.4 1.000   1.079 1.081 -0.002 0.998   108.77 85.58 23.19 1.271
7 A A   1395 1356 39.3 1.029   1.188 1.146 0.042 1.037   13.16 2.95 10.21 4.455
8 A A   1301 1275 26.7 1.021   1.842 1.924 -0.081 0.958   25.72 14.74 10.98 1.745
9 A A   1156 1107 49.2 1.044   2.720 2.718 0.002 1.001   289.95 241.12 48.83 1.203
10 A A   1089 1035 53.8 1.052   1.577 1.489 0.088 1.059   1.10 3.58 -2.48 0.307
11 A A   654 683 -28.9 0.958   1.246 1.291 -0.045 0.965   214.50 172.54 41.96 1.243
12 A A   628 602 26.7 1.044   3.429 3.292 0.137 1.042   61.10 29.99 31.12 2.038
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.