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Compare vibrational frequencies for two calculations for H2Ar (H2 Ar 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 Σ Σ   4175 4275 -100.4 0.977   1.008 1.008 0.000 1.000   0.01 0.03 0.174
2 Σ Σ   27 48 -21.2 0.557   1.057 1.057 0.000 1.000   0.00 0.02 0.202
3 Π Π   32 78 -45.2 0.418   1.008 1.008 -0.000 1.000   0.00 0.00 0.636
4 Π Π   32 78 -45.2 0.418   1.008 1.008 -0.000 1.000   0.00 0.00 0.636
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.