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Compare vibrational frequencies for two calculations for H2OCH3OCH3 (water dimethylether 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   3740 3655 85.1 1.023   1.080 1.076 0.003 1.003   133.56 105.82 1.262
2 A A   3626 3494 131.3 1.038   1.049 1.050 -0.002 0.998   185.14 230.85 0.802
3 A A   2987 3057 -69.9 0.977   1.100 1.102 -0.002 0.999   29.33 10.73 2.733
4 A A   2976 3041 -65.0 0.979   1.100 1.102 -0.002 0.998   42.01 20.49 2.051
5 A A   2912 2971 -58.5 0.980   1.106 1.108 -0.002 0.998   132.60 13.65 9.712
6 A A   2910 2964 -54.2 0.982   1.107 1.106 0.000 1.000   15.99 82.40 0.194
7 A A   2870 2901 -31.1 0.989   1.037 1.035 0.002 1.002   63.02 45.41 1.388
8 A A   2858 2894 -36.7 0.987   1.035 1.033 0.002 1.001   46.38 39.29 1.180
9 A A   1662 1665 -2.3 0.999   1.079 1.078 0.001 1.001   97.12 73.47 1.322
10 A A   1499 1488 10.5 1.007   1.091 1.061 0.030 1.029   0.24 0.96 0.247
11 A A   1484 1474 10.3 1.007   1.058 1.054 0.004 1.003   7.93 11.90 0.666
12 A A   1483 1469 14.4 1.010   1.060 1.055 0.004 1.004   9.06 13.10 0.691
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.