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

Compare vibrational frequencies for two calculations for HCOOHH2O (Formic acid water dimer)

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   3735 3634 101.6 1.028   1.080 1.075 0.005 1.004   128.30 98.96 29.34 1.296
2 A A   3616 3455 160.3 1.046   1.049 1.052 -0.003 0.997   104.51 160.12 -55.61 0.653
3 A A   3436 3127 309.5 1.099   1.066 1.066 -0.000 1.000   487.21 565.80 -78.59 0.861
4 A A   2978 2982 -3.1 0.999   1.094 1.092 0.002 1.002   76.45 97.96 -21.52 0.780
5 A A   1794 1705 89.2 1.052   6.895 5.120 1.775 1.347   465.42 260.50 204.92 1.787
6 A A   1645 1644 0.7 1.000   1.084 1.113 -0.029 0.974   143.35 141.74 1.61 1.011
7 A A   1414 1419 -4.5 0.997   1.187 1.260 -0.073 0.942   5.03 1.47 3.56 3.415
8 A A   1371 1348 22.5 1.017   1.465 1.262 0.203 1.161   28.80 12.37 16.43 2.329
9 A A   1206 1181 24.6 1.021   3.498 4.197 -0.699 0.833   281.24 218.12 63.12 1.289
10 A A   1082 1031 50.7 1.049   1.592 1.355 0.236 1.174   0.73 27.50 -26.77 0.026
11 A A   842 926 -83.9 0.909   1.143 1.272 -0.129 0.899   239.51 151.56 87.95 1.580
12 A A   672 682 -10.4 0.985   4.159 2.294 1.865 1.813   66.83 166.16 -99.33 0.402
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.