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

Compare vibrational frequencies for two calculations for PO2 (Phosphorus dioxide)

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 A1 A1   1085 1025 60.5 1.059   17.015 17.120 -0.105 0.994   5.27 7.64 -2.38 0.689
2 A1 A1   411 386 25.3 1.066   19.643 19.506 0.138 1.007   54.20 39.11 15.09 1.386
3 B2 B2   1309 1528 -218.7 0.857   20.671 20.713 -0.042 0.998   146.57 379.92 -233.35 0.386
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.