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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 1.751 0.202 -0.696 0.234 -0.127 1.819
  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 101.2 1.028   1.080 1.075 0.005 1.004   128.30 99.10 1.295
2 A A   3616 3457 158.7 1.046   1.049 1.052 -0.003 0.997   104.51 158.16 0.661
3 A A   3436 3130 305.9 1.098   1.066 1.066 -0.000 1.000   487.21 564.51 0.863
4 A A   2978 2982 -3.2 0.999   1.094 1.092 0.002 1.002   76.45 96.65 0.791
5 A A   1794 1705 89.3 1.052   6.895 5.144 1.340   465.42 260.71 1.785
6 A A   1645 1644 0.6 1.000   1.084 1.112 -0.028 0.975   143.35 141.06 1.016
7 A A   1414 1418 -4.0 0.997   1.187 1.259 -0.073 0.942   5.03 1.41 3.572
8 A A   1371 1348 22.7 1.017   1.465 1.263 1.160   28.80 12.31 2.339
9 A A   1206 1181 25.2 1.021   3.498 4.194 0.834   281.24 218.42 1.288
10 A A   1082 1031 51.0 1.049   1.592 1.358 1.172   0.73 26.90 0.027
11 A A   842 925 -82.9 0.910   1.143 1.270 0.900   239.51 152.03 1.575
12 A A   672 682 -9.5 0.986   4.159 2.340 1.777   66.83 162.39 0.412
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.